Liquid crystal composition, liquid crystal device using the composition liquid crystal apparatus and display method

ABSTRACT

A liquid crystal composition includes at least one fluorine-containing mesomorphic compound (a) having a fluorocarbon terminal portion and a hydrocarbon terminal portion, and at least one optically active compound (b) having at least one substituted or unsubstituted terminal alkyl group containing an asymmetric carbon atom directly connected with F, CF 3  or CH 3 . The liquid crystal composition shows a layer structure of so-called bookshelf or a layer structure having a small inclination angle (closer to bookshelf structure). The liquid crystal composition is useful in improving response characteristics and display characteristics, particularly a contrast ratio, of a liquid crystal device using the liquid crystal composition.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to a liquid crystal composition,particularly a chiral smectic liquid crystal composition, and a liquidcrystal device using the liquid crystal composition suitable for use inflat-panel displays, projection displays, etc. The present inventionalso relates to a liquid crystal apparatus using the device particularlyas a display device, and a display method using the composition.

There has been known a cathode ray tube (CRT) as a display device. TheCRT has widely been used as a display terminal for outputting motionpictures of a television receiver or a video tape recording (VTR)apparatus or used as a monitor for a personal computer. However, the CRTencounters problems when outputs still images, in view of itscharacteristics, such that visibility or observability is liable to belowered by, e.g., scanning fringe due to flicker or insufficientresolution and that degradation or deterioration of a fluorescentsubstance due to a surface memory is caused to occur in some cases. Inrecent years, it has been found that an electromagnetic wave generatedby the CRT adversely affects the human body. As a result, the CRT canbreak the health of video display terminal (VDT) operators in somecases. In addition, the CRT has a structure including a large volumebehind a picture area (display portion), whereby space-savingutilization of an office or a house in which the CRT is used ishindered.

Liquid crystal devices have been used as a display device having solvedthe above-mentioned problems of the CRT. For instance, there have beenknown liquid crystal devices using use TN (twisted nematic) type liquidcrystals, as shown in "Voltage-Dependent Optical Activity of a TwistedNematic Liquid Crystal" by M. Schadt and W. Helfrich "Applied PhysicsLetters" Vol. 18, No. 4 (Feb. 15, 1971) pp. 127-128.

One of the above-mentioned TN-type liquid crystal devices is a simplematrix-type liquid crystal device having the advantage of inexpensiveproduction costs. When the liquid crystal device is driven by using anelectrode matrix structure with an improved pixel density in accordancewith a multiplex driving scheme, the liquid crystal device is liable toencounter a problem of occurrence of crosstalk, so that the number ofpixels is restricted. Further, the uses of the device as a displaydevice is also limited since the response speed is too slow, i.e., onthe order of at least several ten milli-seconds.

In recent years, there have been proposed liquid crystal devices using athin film transistor (TFT). These liquid crystal devices can control adisplay state pixel by pixel since each pixel is provided with atransistor, whereby the devices solve problems of crosstalk and responsespeed. However, as these devices have a larger picture area, it isindustrially more difficult to prepare a liquid crystal device with nodefective pixels. Even if it is possible to prepare such a liquidcrystal device, the device is more expensive.

To overcome the above-mentioned drawbacks of such conventional liquidcrystal devices, the use of liquid crystal devices using a liquidcrystal material having bistability has been proposed by Clark andLagerwall (e.g. Japanese Laid-Open Patent Appln. (JP-A) No. 56-107216;U.S. Pat. No. 4,367,924, etc.) In this instance, as the liquid crystalmaterial having bistability, a ferroelectric liquid crystal havingchiral smectic C-phase (SmC*) or H-phase (SmH*) is generally used. Theferroelectric liquid crystal can effect inversion switching due to itsspontaneous polarization, thus showing a very high response speed.Further, the ferroelectric liquid crystal shows bistable states(bistability) having a memory characteristic and is excellent in viewangle characteristics, so that a liquid crystal device using aferroelectric liquid crystal is considered suitable for a display deviceor light-valve having properties including high-speed responsiveness,high resolution and a large picture area. In recent years, there hasbeen proposed an anti-ferroelectric chiral smectic liquid crystal deviceusing three stable states, as described in "Japanese Journal of AppliedPhysics" vol. 27, p. L729 (1988) by Chanani and Takezoe et al.

Such a liquid crystal device using a chiral smectic liquid crystal,however, encounters a problem such that a contrast ratio is lowered byoccurrence of a zig-zag alignment defect in some cases, as described in"Structures and Properties of Ferroelectric Liquid Crystals" (1990) byAtsuo Fukuda and Hideo Takezoe issued by Corona Publishing Co. Ltd.(Tokyo Japan). The reason why the zigzag defect occurs may beattributable to the fact that a layer of a chiral smectic liquid crystaldisposed between a pair of substrates constituting a cell structureincludes two kinds of chevron layer structures.

On the other hand there has been the recent trend in layer structure ofa (chiral smectic) liquid crystal wherein a high contrast ratio isintended to be realized by suppressing a chevron layer structureresulting in a low contrast ratio and providing the liquid crystal witha bookshelf layer structure (hereinafter referred to as "bookshelfstructure") in which boundaries of each liquid crystal molecular layerare disposed in parallel with each other (i.e., like a bookshelf) orwith a structure closer to the bookshelf structure (e.g., Atsuo Fukuda(Editor)) Future Liquid Crystal Display and Its Materials (ZisedaiEkisho Display To Ekisho Zairyo)" (1992), issued by K.K. CMC (TokyoJapan). One of methods for realizing a bookshelf structure is a methodof using a naphthalene-based liquid crystal material having a particularstructure. In this method, however, the resultant liquid crystal devicehas a tilt angle of about 10 degrees, which is considerably smaller thanan ideal tilt angle of 22.5 degrees providing a maximum transmittance,thus resulting in a low transmittance or a low contrast. In addition,such a liquid crystal material fails to exhibit a bookshelf structurereversibly with respect to temperature in many cases. Another method forgiving a bookshelf structure may include one inducing a bookshelfstructure by externally applying an electric field to a liquid crystaldevice. Such a method, however, involves a problem of unstabilityagainst external stimuli such as temperature. In addition, various otherproblems are presumably present in order to put a liquid crystalmaterial exhibiting a bookshelf structure into practical use since sucha material has just discovered or proposed.

Further, in quite recent years, there have been proposed a mesomorphic(liquid crystal) compound having a perfluoroether terminal portion (U.S.Pat. No. 5,262,082 and International Publication No. WO93/22396) orhaving a perfluoroalkyl terminal portion (U.S. Pat. No. 5,082,587) and achiral smectic liquid crystal composition (Marc D. Radcliffe et al. The4th International Ferroelectric Liquid Crystal Conference, P-46 (1993))as materials exhibiting a bookshelf structure or a structure closerthereto. By using these liquid crystal materials, it is possible toprovide a bookshelf structure or a structure showing a small layerinclination angle and being closer to the bookshelf structure withoutusing external fields such as an external electric field. These liquidcrystal materials also provide a larger tilt angle.

However, these liquid crystal materials (compounds and compositions) areliable to exhibit poor solubility with other many mesomorphic (liquidcrystal) compounds due to its particular denser molecular structure andprovide an insufficient response speed attributable to a larger tiltangle in some cases.

Accordingly, there have been desired to provide a chiral smectic (orferroelectric) liquid crystal composition suitable for a liquid crystaldevice showing good switching (driving) characteristics by selectingsuch a chiral smectic liquid crystal composition as to comprise amesomorphic (liquid crystal) compound exhibit a bookshelf structure of aliquid crystal layer or a structure having a layer inclination anglecloser thereto and comprise a chiral dopant (chiral doping substance)having a sufficient solubility with the mesomorphic compound andinducing a large spontaneous polarization in combination.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystalcomposition, particularly a chiral smectic liquid crystal compositionshowing a good alignment state and stably exhibiting a bookshelfstructure or a structure, having a small layer inclination angle, closerto the bookshelf structure with respect to a liquid crystal layerstructure, thereby to realize a liquid crystal device having improvedproperties such as high responsiveness, high contrast, high definitionand high brightness.

Another object of the present invention is to provide a liquid crystalcomposition having an excellent mutual solubility between componentsthereof to stably exhibit the above required characteristics.

Another object of the present invention is to provide a large-arealiquid crystal device having the above-mentioned improved properties byusing the above liquid crystal composition, a liquid crystal apparatusparticularly a liquid crystal display apparatus showing excellentdisplay characteristics by using the above liquid crystal device, and adisplay method using the above liquid crystal composition or the liquidcrystal device.

According to the present invention, there is provided a liquid crystalcomposition, comprising:

at least one fluorine-containing mesomorphic compound (a) comprising afluorocarbon terminal portion and a hydrocarbon terminal portion, theterminal portions being connected by a central core, the compound (a)having smectic phase or having latent smectic phase; and

at least one optically active compound (b) represented by the followingformula (II):

    R.sub.O --A.sub.O --R.sub.1                                (II),

wherein A₀ is a mesogen group comprising one to four divalent groupseach connected directly or by a bonding group and each capable of havingone or two substituents comprising F, Cl, Br, CH₃, CF₃ and/or CN, thedivalent group being selected from the group consisting of1,4-phenylene; pyridine-2,5-diyl; pyrimidine-2,5-diyl;pyrazine-2,5-diyl; pyridazine-3,6-diyl; 1,4-cyclohexylene;1,3-dioxane-2,5-diyl; 1,3-dithiane-2,5-diyl; thiophene-2,5-diyl;thiazole-2,5-diyl; thiadiazole-2,5-diyl; benzoxazole-2,5-diyl;benzoxazole-2,6-diyl; benzothiazole-2,5-diyl; benzothiazole-2,6-diyl;benzofuran-2,5-diyl; benzofuran-2,6-diyl quinoxaline-2,6-diyl;quinoline-2,6-diyl; 2,6-naphthylene; indan-2,5-diyl;2-alkylindan-2,5-diyl having a linear or branched alkyl group having1-18 carbon atom; indanone-2,6-diyl; 2-alkylindanone-2,6-diyl having alinear or branched alkyl group having 1-18 carbon atoms;coumaran-2,5-diyl; and 2-alkylcoumaran-2,5-diyl having a linear orbranched alkyl group having 1-18 carbon atoms; and

R₀ and R₁ independently denote a substituted or unsubstituted linear orbranched alkyl group having 1-18; each of the alkyl groups R₀ and R₁being capable of including at least one --CH₂ -- group which can bereplaced by --Y--, --Y--CO--, --CO--Y--, --CO--, --OCOO--, --CH═CH-- or--CC.tbd.C-- in which Y is O or S; and at least one of R₀ and R₁ havingat least one asymmetric carbon atom directly connected with F, CF₃ orCH₃.

The present invention provides a liquid crystal device comprising a pairof opposite electrode plates and the liquid crystal compositiondescribed above disposed between the electrode plates.

The present invention further provides a liquid crystal apparatusincluding the liquid crystal device, particularly including a displaypanel comprising the liquid crystal device.

The present invention still further provides a display method using theliquid crystal composition described above and controlling the alignmentdirection of liquid crystal molecules in accordance with image data toeffect display.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a liquid crystal device using aliquid crystal composition according to the present invention.

FIG. 2 is a block diagram showing a display apparatus comprising aliquid crystal device utilizing a liquid crystal composition and agraphic controller according to the present invention.

FIG. 3 is a time chart of image data communication showing timecorrelation between signal transfer and driving with respect to a liquidcrystal display apparatus and a graphic controller.

FIG. 4 is a view showing a switching signal used in driving conditionsadopted in Examples appearing hereinafter.

DETAILED DESCRIPTION OF THE INVENTION

The liquid crystal composition according to the present invention ischaracterized by using the fluorine-containing mesomorphic compound (a)and the optically active (or chiral) compound (b) respectively describedabove in combination.

The liquid crystal composition of the present invention has a goodhomogeneity (or uniformity) due to an excellent mutual solubilitybetween the compound (a) and the compound (b). The liquid crystalcomposition may preferably be a chiral smectic liquid crystalcomposition and more preferably be a ferroelectric liquid crystalcomposition. When the liquid crystal composition of the presentinvention is used in a liquid crystal device, a liquid crystal layer canexhibit a bookshelf structure or a structure closer thereto having asmall layer inclination angle (hereinbelow, sometimes inclusivelyreferred to a "bookshelf structure"), particularly attributable to thecompound (a), without using, e.g., an external electric field, thusrealizing a good alignment state and high-speed responsiveness.

The compound (a) used in the liquid crystal composition of the inventioncontains a fluorocarbon terminal portion, preferably a terminalperfluoroalkyl group or a terminal perfluoroether group. The compound(a) has a smectic phase (or mesophase) or a latent smectic phase (ormesophase). Herein, the compound (a) having a latent smectic phase meansa compound not showing a smectic phase by itself but showing a smecticphase when used together with a compound having a smectic phase oranother compound having a latent smectic phase.

On the other hand, the compound (b) used in combination with thecompound (a) described above is useful in providing a resultant liquidcrystal composition with a chiral smectic phase, i.e., is used as achiral doping substance or a chiral dopant. As a result, the resultantliquid crystal composition provides a high response speed and stablyshows a bookshelf structure while ensuring a mutual solubility betweenthe respective components.

Hereinbelow, the fluorine-containing mesomorphic compound (a) will beexplained more specifically.

The term "mesomorphic compound" used herein covers not only a compoundassuming a mesomorphic (liquid crystal) phase but also a compound notassuming a mesomorphic phase per se as long as a liquid crystalcomposition containing such a compound assumes a mesomorphic phase.

The mesomorphic compound (a) used in the liquid crystal composition ofthe invention may preferably have a fluorocarbon terminal portion of thecompound (a) is --DC_(x) F_(2x+1) or --D(C_(x),F_(2x),O)_(z) C_(y)F_(2y+1) in which

x is 1-20;

x' is independently 1-10 for each C_(x),F_(2x),O group;

y is 1-10;

z is 1-10; and

D is a single bond, --(CH₂)_(r) --, --COO--C_(r) H_(2r) --, --OC_(r)H_(2r) --, --OC_(r) H_(2r) O--C_(r),H_(2r),--, --OSO₂ --, --SO₂ --,--SO₂ --C_(r) H_(2r) --, --C_(r) H_(2r) --N(C_(p) H_(2p+1))--SO₂ --, or--C_(r) H_(2r) --N(C_(p) H_(2p+1))--CO-- wherein r and r' areindependently 1-20, and p is 0-4.

The mesomorphic compound (a) may more preferably have a fluorocarbonterminal portion of --D(C_(x),F_(2x),O)_(z) C_(y) F_(2y+1)(perfluoroether group) in view of ease of providing a bookshelfstructure.

The mesomorphic compound (a) may preferably be represented by thefollowing formula (I): ##STR1## in which B₁, D₁ and F₁ independentlydenote ##STR2## a, b and c independently denote an integer of 0-3 withthe proviso that a+b+c is at least 2;

M₁ and N₁ independently denote --COO--, --OCO--, --COS--, --SCO--,--COSe--, --SeCO--, --COTe--, --TeCO--, .paren open-st.CH₂ CH₂ .parenclose-st._(d) wherein d is an integer of 1-4, --CH═CH--, --CH═N--,--N═CH--, --CH₂ O--, --OCH₂ --, --CO--, --O-- or a single bond;

X, Y and Z independently denote --H, --Cl, --F, --Br, --I, --OH, --OCH₃,--CN, or --NO₂ and l , m and n independently denote an integer of 0-4;

G₁ is --COO--C_(e) H_(2e) --, --O--C_(e) H_(2e) --, --C_(e) H_(2e) --,--OSOO--, --OOSO--, --SOO--, --SOOC_(e) H_(2e) --, --OC_(e) H_(2e)--OC_(e),H_(2e),--, --C_(e) H_(2e) --N(C_(p) H_(2p+1))--SO₂ -- or--C_(e) H_(2e) --N(C_(p) H_(2p+1)) --CO-- wherein e and e' independentlydenote an integer of 1-20 and p is an integer of 0-4;

A₁ is a linear or branched group represented by --O--C_(f) H_(2f)--O--C_(g) H_(2g+1), --C_(f) H_(2f) --O--C_(g) H_(2g+1), --C_(f) H_(2f)--R', --O--C_(f) H_(2f) --R', --COO--C_(f) H_(2f) --R' or --OCO--C_(f)H_(2f) --R' wherein R' is --Cl, --F, --CF₃, --NO₂, --CN, --H,--COO--C_(f),H_(2f'+1) or --OCO--C_(f') H_(2f'+1) in which and f, f' andg independently denote an integer of 1-20; and

R is --C_(x) F_(2x+1) or .paren open-st.C_(x') F_(2x')).parenclose-st._(z') C_(y) F_(2y+1) wherein x is an integer of 1-20, x' isindependently an integer of 1-10 for each C_(x'),F_(2x'),O group, y isan integer of 1-10, and z is an integer of 1-6.

R in the formula (I) may preferably be (C_(x'),F_(2x'),O)_(z') C_(y)F_(2y+1) (perfluoroether group) since the group is more effective inproviding bookshelf structure.

The mesomorphic compound (a) (preferably having the formula (I)) may besynthesized through processes similar to those described in U.S. Pat.Nos. 5,082,587 and 5,262,082 and WO93/22936. Examples of the mesomorphiccompound (a) of the formula (I) may include those shown below. ##STR3##

Among the mesomorphic compounds of the formula (I) as described above, afluorine-containing mesomorphic compound having a phenyl-pyrimidineskeleton and represented by the formula (I') shown below mayparticularly preferably be used since the compound of the formula (I')is effective in providing a resultant liquid crystal composition with achiral smectic C phase in a wide temperature range including roomtemperature and with a low viscosity.

Formula (I') ##STR4## in which n2 is an integer of 5-10; and

R" is --C_(x) F_(2x+1) or (C_(x") F_(2x") O)_(z") C_(y') F_(2y'+1)wherein x is an integer of 1-20, x" is independently an integer of 1--3for each C_(x") F_(2x") O group, y' is an integer of 1-4, and z" is aninteger of 1-3.

By using the mesomorphic compound (a) (preferably having the formulae(I) and (I')), it is possible to provide a liquid crystal compositioncontaining such a compound (a) with a bookshelf structure or a structurehaving a small layer inclination angle closer to that of the bookshelfstructure without using an external electric field. The liquid crystalcomposition shows a high response speed due to its low viscosity andprovides a larger pretilt angle to a liquid crystal device, whereby itis possible to realize a chiral smectic liquid crystal device showing ahigh transmittance.

The liquid crystal composition according to the present invention maypreferably contain at least 30 wt. %, more preferably at least 50 wt. %,of at least one species of a fluorine-containing mesomorphic compound(a) preferably represented by the formula (I) or (I') in order to havethe effects of addition thereof as described above, such as ease ofproviding a bookshelf structure, a large tilt angle and a low viscosity.

In the present invention, as described above, the liquid crystalcomposition may preferably contain the compound (a) having aperfluoroether group as a fluorocarbon terminal portion so as to providea liquid crystal layer structure having a very small layer inclinationangle closer to a bookshelf structure by which a good displaycharacteristic (e.g., high contrast) is attained. The compound (a) maymore preferably have a fluorocarbon terminal portion represented by--D(C_(x') F_(2x') O)_(z) C_(y) F_(2y+1) (x', y and z are the same asmentioned above) and may particularly preferably have theabove-mentioned formula (I) and the terminal group R represented by--(C_(x') F_(2x') O)_(z') C_(y) F_(2y+1) (x', y and z' are the same asdescribed above). In case where the compounds (a) having the aboveperfluoroether group are used, such compounds (a) may preferably becontained in the resultant liquid crystal composition in an amount of atleast 30 wt. %, particularly at least 50 wt. %. Below 30 wt. %, a layerinclination angle of the resultant liquid crystal composition becomestoo large, thus resulting in a poor display characteristic, such as alow contrast. On the other hand, even in the case of using the compound(a) in an amount of at least 30 wt. %, an alignment characteristic islowered when compared with the case of using the compound (a) in anamount below 30 wt. % in some cases. In the present invention, however,such a disadvantage can be remedied by using a specific optically activecompound (b) (as a chiral doping substance) as mentioned above incombination, whereby a bookshelf structure (or a closer structurethereto) can be provided stably to allow a uniform alignment state.

Hereinbelow, the optically active compound (b) Of the formula (II) usedtogether with the mesomorphic compound (a) will be explained in detail.

The optically active compound (b) may be a mesomorphic compound, and thecompound (b) is used as a chiral dopant and has at least one symmetriccarbon atom directly connected with F, CF₃ or CH₃ as mentioned above.Such a chiral dopant (the compound (b)) having the particular asymmetriccarbon atom has a good solubility with the above-mentioned mesomorphiccompound (a), particularly those of the formulae (I) and (I'), having aterminal perfluoroalkyl group or a terminal perfluoroether group and hasa prescribed spontaneous polarization-imparting property. As a result, aresultant (chiral smectic) liquid crystal composition according to thepresent invention provides good driving characteristics including a highcontrast ratio and an excellent switching characteristic based on theformation of a bookshelf structure of a structure closer thereto havinga small layer inclination angle.

In the formula (II) representing the compound (b), either one or both ofR₀ and R₁ may preferably be represented by any one of the followingformulae: ##STR5## in which R³⁵ is a linear or branched alkyl grouphaving 1-18 carbon atoms; R³³ is --CH₂ -- or --CO--; R³⁴ is H or CH₃ ;X³³ is a single bond or --CH₂ -- when R³³ is --CO--, or X³³ is a singlebond, --CO-- or --CH₂ -- when R³³ is --CH₂ --; and C* is an asymmetriccarbon atom ##STR6## in which R⁴³ is a linear or branched alkyl grouphaving 1-10 carbon atoms; X⁴³ is --O--, --COO--, --OCH₂ --, --OCH₂ CH₂--, --OCOCH₂ --, --CH₂ O--, --COOCH₂ CH₂ --, --CH₂ OCH₂ CH₂ or --CH₂COOCH₂ --; and C* is an asymmetric carbon atom; and ##STR7## in whichR⁵³ is a linear or branched alkyl group having 1-18 carbon atoms; L52 is0 or 1; X⁵³ is a single bond, --CO-- or --CH₂ -- when L52 is 0, or X⁵³is a single bond or --CH₂ -- when L52 is 1; X⁵⁴ is --COO--, or --0--;L53 is 0 or 1; and C* is an asymmetric carbon atom.

Such groups R₀ and R₁ is particularly effective in imparting a largespontaneous polarization to the resultant liquid crystal composition.

In the formula (II) representing the optically active compound (b), bothof R₀ and R₁ may be an alkyl group having an asymmetric carbon atomdirectly connected with F, CF₃ or CH₃.

The optically active compound (b) represented by the formula (II) usedin the present invention may preferably include at least one species ofan optically active compound represented by any one of the followingformulae (III), (IV), (V) and (VI).

Compound (b) of the formula (III) ##STR8## in which R³² is a linear orbranched alkyl group having 1-18 carbon atoms capable of including atleast one --CH₂ -- group which can be replaced by --Y³ --, --Y³ --CO--,--CO--Y³ --, --CO--, --OCOO--, --CH═CH-- or --C.tbd.C-- wherein Y³ is Oor S;

R³⁵ is a linear or branched alkyl group having 1-18 carbon atoms;

m32 is 0, 1 or 2;

R³³ is --CH₂ -- or --CO--;

R³⁴ is H or CH₃ ;

A³², A³³ and A³⁴ independently denote a single bond, 1,4-phenylene;pyridine-2,5-diyl; pyrimidine-2,5-diyl; pyrazine-2,5-diyl;pyridazine-3,6-diyl; 1,4-cyclohexylene; 1,3-dioxane-2,5-diyl;1,3-dithiane-2,5-diyl; thiophene-2,5-diyl; thiazole-2,5-diyl;thiadiazole-2,5-diyl; benzoxazole-2,5-diyl; benzoxazole-2,6-diyl;benzothiazole-2,5-diyl; benzothiazole-2,6-diyl; benzofuran-2,5-diyl;benzofuran-2,6-diyl; quinoxaline-2,6-diyl; quinoline-2,6-diyl;2,6-naphthylene; indan-2,5-diyl; 2-alkylindan-2,5-diyl having a linearor branched alkyl group having 1-18 carbon atom; indanone-2,6-diyl;2-alkylindanone-2,6-diyl having a linear or branched alkyl group having1-18 carbon atoms; coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl havinga linear or branched alkyl group having 1-18 carbon atoms;

X³² is a single bond, --COO--, --OCO--, --CH₂ O-- or --OCH₂ --;

X³³ is a single bond or --CH₂ --when R³³ is --CO--, or X³³ is a singlebond, --CO-- or --CH₂ --when R³³ is --CH₂ --;

C* is an asymmetric carbon atom; and

A³², A³³ and A³⁴ each may have one or two substituents comprising F, Cl,Br, CH₃, CF₃ and/or CN.

Examples of the compound (b) of the formula (III) may include those asdescribed in JP-A Nos. 62-093248, 62-198633, 63-088161, 63-104949,63-107951, 63-122651, 63-022042, 63-192732, 63-196553, 63-196571,63-215661, 63-216878, 63-218647, 63-225337, 63-243059, 63-303951,64-022990, 1-272571, 64-031740, 1-121244, 1-207280, 1-038077, 1-265052,2-028158, 2-069427, 2-069467, 2-115145, 2-000227, 3-227980 and 4-300871.The compound (b) of the formula (III) may be produced through processesas described in these documents.

Specific and preferred examples of the optically active compound (b) ofthe formula (III) may include those represented by the followingstructural formulae (Ex. Comp. Nos. 3-1 to 3-105 indicated as Nos. 1-105in Table 1 below) including abbreviations used for the respective groupslisted below (hereinbelow, the abbreviations in Tables 2-6 represent thesame groups as those in Table 1). In Table 1, the structural formula(Ex. Comp. No. 3-64 indicated as No. 64) has m32 being 2. ##STR9##

                                      TABLE 1                                     __________________________________________________________________________    No.                                                                              R.sup.32    A.sup.32                                                                          A.sup.32                                                                          A.sup.33                                                                          A.sup.34                                                                          X.sup.33                                                                         X.sup.33                                                                         Σ3                                                                        R.sup.34                                                                         R.sup.35                            __________________________________________________________________________     1 C.sub.6 H.sub.13                                                                          --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     2 C.sub.8 H.sub.17 O                                                                        --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.18 H.sub.37                    3 C.sub.5 H.sub.11 O                                                                        --  --  Ph  Ph2F                                                                              -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     4 CH.sub.3 O  --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     5 C.sub.6 H.sub.13 CH(CH.sub.3)(CH.sub.2).sub.2 O                                           --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     6 C.sub.7 H.sub.15 O                                                                        --  --  Ph  Ph23F                                                                             -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     7 C.sub.6 H.sub.13                                                                          --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.9 H.sub.19                     8 C.sub.7 H.sub.15 O                                                                        --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     9 C.sub.8 H.sub.17 O                                                                        --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     10                                                                              C.sub.8 H.sub.17                                                                          --  --  Pr1 Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     11                                                                              C.sub.10 H.sub.21                                                                         --  --  Pr2 Ph  -- M1 Σ3                                                                        H  C.sub.4 H.sub.9                      12                                                                              C.sub.11 H.sub.23                                                                         --  --  Pr2 Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     13                                                                              C.sub.12 H.sub.25                                                                         --  --  Pr2 Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     14                                                                              C.sub.4 H.sub.9 O                                                                         --  --  Py1 Ph  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    15                                                                              C.sub.13 H.sub.27                                                                         --  --  Py2 Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     16                                                                              C.sub.6 H.sub.13                                                                          --  --  Py2 Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     17                                                                              C.sub.6 H.sub.13 CH(CH.sub.3)CH.sub.2 O                                                   --  --  Py2 Ph  -- M1 Σ3                                                                        H  C.sub.9 H.sub.19                     18                                                                              C.sub.5 H.sub.11 O                                                                        --  --  Py2 Ph23F                                                                             -- M1 Σ3                                                                        H  C.sub.4 H.sub.9                      19                                                                              C.sub.10 H.sub.21                                                                         --  --  Py2 Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     20                                                                              C.sub.8 H.sub.17                                                                          --  --  Py2 Ph3F                                                                              -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     21                                                                              C.sub.6 H.sub.13                                                                          --  --  Cy  Ph  -- M1 Σ3                                                                        H  C.sub.4 H.sub.9                      22                                                                              C.sub.3 H.sub.7                                                                           --  --  Cy  Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     23                                                                              C.sub.5 H.sub.11                                                                          --  --  Cy  Ph  -- M1 Σ3                                                                        H  C.sub.14 H.sub.29                    24                                                                              C.sub.10 H.sub.21                                                                         --  --  Cy  Ph  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    25                                                                              C.sub.6 H.sub.13                                                                          --  --  Pa  Ph  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    26                                                                              C.sub.7 H.sub.15 OCO                                                                      --  --  Pd  Ph  -- M1 Σ3                                                                        H  C.sub.3 H.sub.7                      27                                                                              C.sub.6 H.sub.13                                                                          --  --  Dt2 Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     28                                                                              C.sub.8 H.sub.17                                                                          --  --  Tn  Ph  -- M1 Σ3                                                                        H  C.sub.9 H.sub.19                     29                                                                              C.sub.5 H.sub.11                                                                          --  --  Tz1 Ph  -- M1 Σ3                                                                        H  C.sub.9 H.sub.19                     30                                                                              C.sub.9 H.sub.19 O                                                                        --  --  Tz2 Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     31                                                                              C.sub.2 H.sub.5                                                                           --  --  Td  Ph  -- M1 Σ3                                                                        H  C.sub.7 H.sub.15                     32                                                                              C.sub.10 H.sub.21                                                                         --  --  Dx2 Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     33                                                                              C.sub.6 H.sub.13                                                                          --  --  Boa2                                                                              Ph  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    34                                                                              C.sub.15 H.sub.31                                                                         --  --  Bob2                                                                              Ph  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    35                                                                              C.sub.7 H.sub.15                                                                          --  --  Bta2                                                                              Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     36                                                                              C.sub.16 H.sub.33 O                                                                       --  --  Btb2                                                                              Ph  -- M1 Σ3                                                                        H  C.sub.9 H.sub.19                     37                                                                              C.sub.6 H.sub.13                                                                          --  --  Np  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     38                                                                              C.sub.5 H.sub.11                                                                          --  --  Np  Ph  -- Cb Σ3                                                                        H  C.sub.4 H.sub.9                      39                                                                              C.sub.8 H.sub.17 CH(CH.sub.3)CH.sub.2 O                                                   --  --  Ep1 Ph  -- Cb Σ3                                                                        H  C.sub.6 H.sub.13                     40                                                                              C.sub.4 H.sub.9                                                                           --  --  Ep2 Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     41                                                                              C.sub.6 H.sub.13                                                                          --  --  Gp1 Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     42                                                                              C.sub.7 H.sub.15                                                                          --  --  Gp2 Ph  -- M1 Σ3                                                                        H  C.sub.12 H.sub.25                    43                                                                              C.sub.6 H.sub.13                                                                          --  --  Cm1 Ph  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    44                                                                              C.sub.8 H.sub.17                                                                          --  --  Io1 Ph  -- M1 Σ3                                                                        H  C.sub.12 H.sub.25                    45                                                                              C.sub.18 H.sub.37                                                                         --  --  Id1 Ph  M1 M1 Σ3                                                                        H  C.sub.6 H.sub.13                     46                                                                              C.sub.11 H.sub.23                                                                         --  --  Id1 Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     47                                                                              C.sub.8 H.sub.17                                                                          --  --  Id1 Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     48                                                                              C.sub.5 H.sub.11                                                                          --  --  Id1 Ph2F                                                                              -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     49                                                                              C.sub.6 H.sub.13                                                                          --  --  Tn  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     50                                                                              C.sub.4 H.sub.9 O                                                                         --  --  Tz2 Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     51                                                                              C.sub.12 H.sub.25                                                                         --  --  Btb2                                                                              Ph  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    52                                                                              C.sub.6 H.sub.13 O                                                                        --  --  Btb2                                                                              Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     53                                                                              CH.sub.2CH(CH.sub.2).sub.3 O                                                              --  --  Ep2 Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     54                                                                              C.sub.9 H.sub.19                                                                          --  --  Gp2 Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     55                                                                              C.sub.5 H.sub.11                                                                          --  --  Np  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     56                                                                              C.sub.6 H.sub.13                                                                          Ph  --  Ph  Ph  Cb M1 Σ3                                                                        H  C.sub.6 H.sub.13                     57                                                                              C.sub.8 H.sub.17 COO                                                                      Pr2 --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     58                                                                              C.sub.3 H.sub.7                                                                           Py2 --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.4 H.sub.9                      59                                                                              C.sub.5 H.sub.11                                                                          --  --  Ha2 Ph  -- M1 Σ3                                                                        H  C.sub.4 H.sub.9                      60                                                                              C.sub.6 H.sub.13                                                                          Ph  COO --  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     61                                                                              C.sub.9 H.sub.19                                                                          Ph  --  Pr1 Ph  -- Cb Σ3                                                                        H  C.sub.6 H.sub.13                     62                                                                              C.sub.13 H.sub.27                                                                         Ph  --  Cy  Ph3Br                                                                             M1 Cb Σ3                                                                        H  C.sub.5 H.sub.11                     63                                                                              C.sub.10 H.sub.21 O                                                                       Ph  OCO Py1 Ph  -- M1 Σ3                                                                        My C.sub.6 H.sub.13                     64                                                                              C.sub.7 H.sub.15                                                                          Ph  --  Py2 Ph  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     65                                                                              C.sub.4 H.sub.9                                                                           Ph3TF                                                                             COO --  Ph  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     66                                                                              CH.sub.3    --  --  Hb2 Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     67                                                                              C.sub.8 H.sub.17                                                                          Ph  --  Tn  Ph  -- M1 Σ3                                                                        H  (CH.sub.2).sub.3 CH(CH.sub.3).su                                              b.2                                  68                                                                              C.sub.2 H.sub.5                                                                           Ph  --  Tz1 Ph2M                                                                              -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     69                                                                              C.sub.6 H.sub.13                                                                          Ph  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     70                                                                              C.sub.10 H.sub.21                                                                         Ph  --  Td  Ph  -- M1 Σ3                                                                        H  (CH.sub.2).sub.3 CH(CH.sub.3).su                                              b.2                                  71                                                                              C.sub.10 H.sub.21                                                                         --  --  Ph  Py1 -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     72                                                                              C.sub.6 H.sub.13                                                                          --  --  Ph  Py1 -- M1 Σ3                                                                        H  C.sub.4 H.sub.9                      73                                                                              C.sub.6 H.sub.13 OCO                                                                      --  --  Ph  Py1 -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     74                                                                              C.sub.7 H.sub.15                                                                          --  --  Ph  Pr2 -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     75                                                                              C.sub.9 H.sub.19                                                                          --  --  Ph  Pr2 -- M1 Σ3                                                                        H  (CH.sub.2).sub.3 CH(CH.sub.3).su                                              b.2                                  76                                                                              C.sub.7 H.sub.15                                                                          --  --  Ph  Pr2 -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     77                                                                              C.sub.5 H.sub.11 O                                                                        --  --  Py2 Cy  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    78                                                                              C.sub.4 H.sub.9                                                                           --  --  Ph  Cy  -- M1 Σ3                                                                        H  C.sub.12 H.sub.25                    79                                                                              C.sub.12 H.sub.25                                                                         --  --  Ph  Cy  -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     80                                                                              C.sub.6 H.sub.13 CC                                                                       --  --  Ph  Pa  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    81                                                                              C.sub.8 H.sub.17 O                                                                        --  --  Ph  Pd  -- M1 Σ3                                                                        My C.sub.6 H.sub.13                     82                                                                              C.sub.3 H.sub.7                                                                           --  --  Ph2Cl                                                                             Tn  -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                    83                                                                              C.sub.4 H.sub.9                                                                           --  --  Ph  Tn  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     84                                                                              C.sub.8 H.sub.17                                                                          --  --  Ph  Tz1 -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     85                                                                              C.sub.4 H.sub.9 OCH(CH.sub.3)COO                                                          --  --  Ph  Tz1 -- M1 Σ3                                                                        H  C.sub.7 H.sub.15                     86                                                                              C.sub.6 H.sub.13                                                                          --  --  Ph2F                                                                              Td  -- M1 Σ3                                                                        My (CH.sub.2).sub.3 CH(CH.sub.3)C.s                                              ub.6 H.sub.13                        87                                                                              C.sub.5 H.sub.11                                                                          --  --  Py2 Np  -- M1 Σ3                                                                        H  C.sub.9 H.sub.19                     88                                                                              CH.sub.3    --  --  Ph  Np  -- M1 Σ3                                                                        H  C.sub.12 H.sub.25                    89                                                                              C.sub.11 H.sub.23                                                                         --  --  Ph  Np  -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     90                                                                              C.sub.5 H.sub.11                                                                          --  --  Py1 Ep1 -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     91                                                                              C.sub.8 H.sub.17 OC.sub.2 H.sub.4                                                         --  --  Ph  Ep1 -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     92                                                                              C.sub.6 H.sub.13                                                                          --  --  Ph  Ep1 -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     93                                                                              C.sub.9 H.sub.19                                                                          --  --  Py1 Gp1 -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                     94                                                                              C.sub.8 H.sub.17                                                                          --  --  Ph  Gp1 -- M1 Σ3                                                                        H  C.sub.6 H.sub.13                     95                                                                              C.sub.3 H.sub.7 COO                                                                       --  --  Ph  Gp1 -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     96                                                                              C.sub.4 H.sub.9                                                                           --  --  Ph  Id1 -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     97                                                                              C.sub.12 H.sub.25                                                                         --  --  Ph  Io1 Cb M1 Σ3                                                                        H  C.sub.6 H.sub.13                     98                                                                              C.sub.10 H.sub.21                                                                         --  --  Ph  Cm1 -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                     99                                                                              C.sub.6 H.sub.13                                                                          --  --  Ph  Ph  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                    100                                                                              C.sub.3 H.sub.7                                                                           Ph  OCH.sub.2                                                                         --  Py1 -- M1 Σ3                                                                        H  C.sub.12 H.sub.25                   101                                                                              C.sub.4 H.sub.9                                                                           Ph2CN                                                                             --  Ph  Pr1 -- M1 Σ3                                                                        H  C.sub.10 H.sub.21                   102                                                                              C.sub.5 H.sub.11                                                                          Ph  CH.sub.2 O                                                                        Ph3F                                                                              Tz1 Cb M1 Σ3                                                                        H  C.sub.6 H.sub.13                    103                                                                              C.sub.6 H.sub.13                                                                          Ph  --  Ph  Tn  -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                    104                                                                              C.sub.7 H.sub.15                                                                          Tn  --  Ph  Py1 -- M1 Σ3                                                                        H  C.sub.8 H.sub.17                    105                                                                              C.sub.10 H.sub.21                                                                         Ph  --  Ph  Cy1 -- M1 Σ3                                                                        H  C.sub.5 H.sub.11                    __________________________________________________________________________

The optically active compound (b) may particularly preferably berepresented by the formula (III) wherein R³² and R³⁵ independentlydenote a linear or branched alkyl group; m32 is 0; R³³ is --CH₂ -- or--CO--; R³⁴ is H or CH₃ ; A³³ is ; ##STR10## A³⁴ is ##STR11## and X³³ isa single bond or --C₂ -- when R³³ is --CO--, or X³³ is a single bond,--CO-- or --C₂ -- when Such a compound (b) is effective in allowing alow viscosity and a wide temperature range showing a chiral smecticphase to the resultant liquid crystal composition de to itsphenyl-pyrimidine skeleton.

Compound (b) of the formula ##STR12## in which R⁴² is a linear orbranched alkyl group having 1-18 carbon atoms capable of including atleast one --CH₂ -- group which can be replaced by --Y⁴ --, --Y⁴ --CO--,--CO--Y⁴ --, --CO--, --OCOO--, --CH═CH-- or --C.tbd.C-- wherein Y⁴ is Oor S;

R⁴³ is a linear or branched alkyl group having 1-10 carbon atoms;

m42 is 0, 1 or 2;

A⁴², A⁴³ and A⁴⁴ independently denote a single bond 1,4-phenylene;pyridine-2,5-diyl; pyrimidine-2,5-diyl; pyrazine-2,5-diyl;pyridazine-3,6-diyl; 1,4-cyclohexylene; 1,3-dioxane-2,5-diyl;1,3-dithiane-2,5-diyl; thiophene-2,5-diyl; thiazole-2,5-diyl;thiadiazole-2,5-diyl; benzoxazole-2,5-diyl; benzoxazole-2,6-diyl;benzothiazole-2,5-diyl; benzothiazole-2,6-diyl; benzofuran-2,5-diyl;benzofuran-2,6-diyl; quinoxaline-2,6-diyl; quinoline-2,6-diyl;2,6-naphthylene; indan-2,5-diyl; 2-alkylindan-2,5-diyl having a linearor branched alkyl group having 1-18 carbon atom; indanone-2,6-diyl;2-alkylindanone-2,6-diyl having a linear or branched alkyl group having1-18 carbon atoms; coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl havinga linear or branched alkyl group having 1-18 carbon atoms;

X⁴² is a single bond, --COO--, --OCO--, --CH₂ O-- or --OCH₂ --;

X⁴³ is --O--, --COO--, --OCH₂ --, --OCH₂ CH₂ --, --OCOCH₂ --, --CH₂ O--,--COOCH₂ CH₂ --, --CH₂ OCH₂ CH₂ -- or --CH₂ COOCH₂ ;

C* is an asymmetric carbon atom; and

A⁴², A⁴³ and A⁴⁴ each may have one or two substituents comprising F, Cl,Br, CH₃, CF₃ and/or CN.

Examples of the compound (b) of the formula (IV) may include those asdescribed in JP-A Nos. 1-160986, 1-242543, 2-000127, 2-069440, 2-295943,3-043488, 3-058980 3-083971, 3-193774, 3-223232, 3-236353, 4-013797,4-253789 and 4-264052. The compound (b) of the formula (IV) may beproduced through processes as described in these documents.

Specific and preferred examples of the optically active compound (b) ofthe formula (IV) may include those represented by the followingstructural formulae (Ex. Comp. Nos. 4-1 to 4-105 indicated as Nos. 1-105in Table 2 below) including abbreviations used for the respective groupslisted below in addition to those listed for Table 1. In Table 2, thestructural formula (Ex. Comp. No. 4-60 indicated as No. 60) has m42being 2.

Om: --OCH₂ --Od: --OCH₂ CH₂ --Em: --OCOCH₂ --

Mo: --CH₂ --O--Ced: --COOCH₂ CH₂ --

Mod:--CH₂ OCH₂ CH₂ --Mce: --CH₂ COOCH₂ -- ##STR13##

Mcd: --CH₂ --O--CH₂

                                      TABLE 2                                     __________________________________________________________________________     ##STR14##                                                                    No.                                                                              R.sup.42    A.sup.42                                                                          A.sup.43                                                                          X.sup.42                                                                          A.sup.44                                                                          A.sup.43                                                                         Σ4                                                                        R.sup.43                                  __________________________________________________________________________     1 C.sub.6 H.sub.13                                                                          Ph  Ph  --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           2 C.sub.8 H.sub.17 O                                                                        Ph  Ph  --  --  Mo Σ4                                                                        C.sub.8 H.sub.17                           3 C.sub.5 H.sub.11 O                                                                        Ph  Ph2F                                                                              --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           4 CH.sub.3 O  Ph  Ph  --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           5 C.sub.6 H.sub.13 CH(CH.sub.3)(CH.sub.2).sub.2 O                                           Ph  Ph  --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           6 C.sub.7 H.sub.15 O                                                                        Ph  P23F                                                                              --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           7 C.sub.6 H.sub.13                                                                          Ph  Ph  --  --  Od Σ4                                                                        C.sub.9 H.sub.19                           8 C.sub.7 H.sub.15 O                                                                        Ph  Ph  --  --  Em Σ4                                                                        C.sub.5 H.sub.11                           9 C.sub.8 H.sub.17 O                                                                        Ph  Ph  --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           10                                                                              C.sub.8 H.sub.17                                                                          Pr1 Ph  --  --  Em Σ4                                                                        C.sub.8 H.sub.17                           11                                                                              C.sub.10 H.sub.21                                                                         Pr2 Ph  --  --  Od Σ4                                                                        C.sub.4 H.sub.9                            12                                                                              C.sub.11 H.sub.23                                                                         Pr2 Ph  --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           13                                                                              C.sub.12 H.sub.25                                                                         Pr2 Ph  --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           14                                                                              C.sub.4 H.sub.9 O                                                                         Py1 Ph  --  --  Em Σ4                                                                        C.sub.10 H.sub.21                          15                                                                              C.sub.12 H.sub.25                                                                         Py2 Ph  --  --  Em Σ4                                                                        C.sub.4 H.sub.9                            16                                                                              C.sub.6 H.sub.13                                                                          Py2 Ph  --  --  Em Σ4                                                                        C.sub.8 H.sub.17                           17                                                                              C.sub.6 H.sub.13 CH(CH.sub.3)CH.sub.2 O                                                   Py2 Ph  --  --  Om Σ4                                                                        C.sub.9 H.sub.19                           18                                                                              C.sub.5 H.sub.11 O                                                                        Py2 P23F                                                                              --  --  Em Σ4                                                                        C.sub.4 H.sub.9                            19                                                                              C.sub.10 H.sub.21                                                                         Py2 Ph  --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           20                                                                              C.sub.8 H.sub.17                                                                          Py2 Ph3F                                                                              --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           21                                                                              C.sub.6 H.sub.13                                                                          Cy  Ph  --  --  Om Σ4                                                                        C.sub.4 H.sub.9                            22                                                                              C.sub.3 H.sub.7                                                                           Cy  Ph  --  --  Em Σ4                                                                        C.sub.5 H.sub.11                           23                                                                              C.sub.5 H.sub.11                                                                          Cy  Ph  --  --  Om Σ4                                                                        C.sub.4 H.sub.9                            24                                                                              C.sub.10 H.sub.21                                                                         Cy  Ph  --  --  Em Σ4                                                                        C.sub.10 H.sub.21                          25                                                                              C.sub.6 H.sub.13                                                                          Pa  Ph  --  --  Om Σ4                                                                        C.sub.10 H.sub.21                          26                                                                              C.sub.7 H.sub.15 OCO                                                                      Pd  Ph  --  --  Om Σ4                                                                        C.sub.3 H.sub.7                            27                                                                              C.sub.6 H.sub.13                                                                          Dt2 Ph  --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           28                                                                              C.sub.8 H.sub.17                                                                          Tn  Ph  --  --  Em Σ4                                                                        C.sub.9 H.sub.19                           29                                                                              C.sub.5 H.sub.11                                                                          Tz1 Ph  --  --  Em Σ4                                                                        C.sub.9 H.sub.19                           30                                                                              C.sub.9 H.sub.19 O                                                                        Tz2 Ph  --  --  Od Σ4                                                                        C.sub.6 H.sub.13                           31                                                                              C.sub.2 H.sub.5                                                                           Td  Ph  --  --  Mo Σ4                                                                        C.sub.7 H.sub.15                           32                                                                              C.sub.10 H.sub.21                                                                         Dx2 Ph  --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           33                                                                              C.sub.6 H.sub.13                                                                          Boa2                                                                              Ph  --  --  Ced                                                                              Σ4                                                                        C.sub.10 H.sub.21                          34                                                                              C.sub.15 H.sub.31                                                                         Bob2                                                                              Ph  --  --  Om Σ4                                                                        C.sub.10 H.sub.21                          35                                                                              C.sub.7 H.sub.15                                                                          Bta2                                                                              Ph  --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           36                                                                              C.sub.16 H.sub.33 O                                                                       Btb2                                                                              Ph  --  --  Em Σ4                                                                        C.sub.9 H.sub.19                           37                                                                              C.sub.6 H.sub.13                                                                          Np  Ph  --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           38                                                                              C.sub.5 H.sub.11                                                                          Np  Ph  --  --  Em Σ4                                                                        C.sub.4 H.sub.9                            39                                                                              C.sub.8 H.sub.17 CH(CH.sub.3)CH.sub.2 O                                                   Ep1 Ph  --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           40                                                                              C.sub.4 H.sub.9                                                                           Ep2 Ph  --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           41                                                                              C.sub.6 H.sub.13                                                                          Gp1 Ph  --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           42                                                                              C.sub.7 H.sub.15                                                                          Gp2 Ph  --  --  Em Σ4                                                                        C.sub.2 H.sub.5                            43                                                                              C.sub.6 H.sub.13                                                                          Cm1 Ph  --  --  Om Σ4                                                                        C.sub.10 H.sub.21                          44                                                                              C.sub.8 H.sub.17                                                                          Io1 Ph  --  --  Om Σ4                                                                        C.sub.2 H.sub.5                            45                                                                              C.sub.18 H.sub.37                                                                         Id1 Ph  --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           46                                                                              C.sub.11 H.sub.23                                                                         Id1 Ph  --  --  Em Σ4                                                                        C.sub.5 H.sub.11                           47                                                                              C.sub.8 H.sub.17                                                                          Id1 Ph  --  --  Od Σ4                                                                        C.sub.5 H.sub.11                           48                                                                              C.sub.5 H.sub.11                                                                          Id1 Ph2F                                                                              --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           49                                                                              C.sub.6 H.sub.13                                                                          Tn  Ph  --  --  Mo Σ4                                                                        C.sub.6 H.sub.13                           50                                                                              C.sub.4 H.sub.9 O                                                                         Tz2 Ph  --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           51                                                                              C.sub.12 H.sub.25                                                                         Btb2                                                                              Ph  --  --  Om Σ4                                                                        C.sub.10 H.sub.21                          52                                                                              C.sub.6 H.sub.13 O                                                                        Btb2                                                                              Ph  --  --  Od Σ4                                                                        C.sub.6 H.sub.13                           53                                                                              CH.sub.2CH(CH.sub.2).sub.3 O                                                              Ep2 Ph  --  --  Om Σ4                                                                        C.sub.5 H.sub.11                           54                                                                              C.sub.9 H.sub.19                                                                          Gp2 Ph  --  --  Mcd                                                                              Σ4                                                                        C.sub.6 H.sub.13                           55                                                                              C.sub.5 H.sub.11                                                                          Np  Ph  --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           56                                                                              C.sub.6 H.sub.13                                                                          Ph  Ph  COO Ph  Od Σ4                                                                        C.sub.6 H.sub.13                           57                                                                              C.sub.8 H.sub.17 COO                                                                      Pr2 Ph  OCO Ph  Om Σ4                                                                        C.sub.5 H.sub.11                           58                                                                              C.sub.3 H.sub.7                                                                           Py2 Ph  --  Ph  Em Σ4                                                                        C.sub.4 H.sub.9                            59                                                                              C.sub.5 H.sub.11                                                                          --  Ha2 --  Ph  Em Σ4                                                                        C.sub.4 H.sub.9                            60                                                                              C.sub.6 H.sub.13                                                                          --  Py2 COO Ph  Em Σ4                                                                        C.sub.6 H.sub.13                           61                                                                              C.sub.9 H.sub.19                                                                          Ph  Py1 --  Ph  Om Σ4                                                                        C.sub.6 H.sub.13                           62                                                                              C.sub.13 H.sub.27                                                                         Ph  Cy  OCO P3Br                                                                              Em Σ4                                                                        C.sub.5 H.sub.11                           63                                                                              C.sub.10 H.sub.21 O                                                                       Ph  Py1 --  Ph  Om Σ4                                                                        C.sub.6 H.sub.13                           64                                                                              C.sub.7 H.sub.15                                                                          Ph  Py2 OCH.sub.2                                                                         Ph  Em Σ4                                                                        C.sub.5 H.sub.11                           65                                                                              C.sub.4 H.sub.9                                                                           Ph3TF                                                                             --  COO Ph  Om Σ4                                                                        C.sub.6 H.sub.13                           66                                                                              CH.sub.3    Hb2 Ph  --  --  Em Σ4                                                                        C.sub.8 H.sub.17                           67                                                                              C.sub.8 H.sub.17                                                                          Ph  Tn  --  Ph  Om Σ4                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub.2        68                                                                              C.sub.2 H.sub.5                                                                           Ph  Tz1 --  Ph2M                                                                              Em Σ4                                                                        C.sub.8 H.sub.17                           69                                                                              C.sub.6 H.sub.13                                                                          Ph  Ph  --  Ph  Om Σ4                                                                        C.sub.8 H.sub.17                           70                                                                              C.sub.10 H.sub.21                                                                         Ph  Td  --  Ph  Em Σ4                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub.2        71                                                                              C.sub.10 H.sub.21                                                                         Ph  Py1 --  --  Mce                                                                              Σ4                                                                        C.sub.6 H.sub.13                           72                                                                              C.sub.6 H.sub.13                                                                          Ph  Py1 --  --  Em Σ4                                                                        C.sub.4 H.sub.9                            73                                                                              C.sub.6 H.sub.13 OCO                                                                      Ph  Py1 --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           74                                                                              C.sub.7 H.sub.15                                                                          Ph  Pr2 --  --  Em Σ4                                                                        C.sub.5 H.sub.11                           75                                                                              C.sub.9 H.sub.19                                                                          Ph  Pr2 --  --  Em Σ4                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub.2        76                                                                              C.sub.7 H.sub.15                                                                          Ph  Pr2 --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           77                                                                              C.sub.5 H.sub.11 O                                                                        Py2 Cy  --  --  Em Σ4                                                                        C.sub.10 H.sub.21                          78                                                                              C.sub.4 H.sub.9                                                                           Ph  Cy  --  --  Om Σ4                                                                        C.sub.2 H.sub.5                            79                                                                              C.sub.12 H.sub.25                                                                         Ph  Cy  --  --  Em Σ4                                                                        C.sub.5 H.sub.11                           80                                                                              C.sub.6 H.sub.13 CC                                                                       Ph  Pa  --  --  Em Σ4                                                                        C.sub.10 H.sub.21                          81                                                                              C.sub.8 H.sub.17 O                                                                        Ph  Pd  --  --  Om Σ4                                                                        C.sub.6 H.sub.13                           82                                                                              C.sub.3 H.sub.7                                                                           Ph2Cl                                                                             Tn  --  --  Em Σ4                                                                        C.sub.10 H.sub.21                          83                                                                              C.sub.4 H.sub.9                                                                           Ph  Tn  --  --  Em Σ4                                                                        C.sub.8 H.sub.17                           84                                                                              C.sub.8 H.sub.17                                                                          Ph  Tz1 --  --  Em Σ4                                                                        C.sub.8 H.sub.17                           85                                                                              C.sub.4 H.sub.9 OCH(CH.sub.3)COO                                                          Ph  Tz1 --  --  Om Σ4                                                                        C.sub.7 H.sub.15                           86                                                                              C.sub.6 H.sub.13                                                                          Ph2F                                                                              Td  --  --  Om Σ4                                                                        (CH.sub.2).sub.3 CH(CH.sub.3)C.sub.6                                          H.sub.13                                   87                                                                              C.sub.5 H.sub.11                                                                          Py2 Np  --  --  Em Σ4                                                                        C.sub.9 H.sub.19                           88                                                                              CH.sub.3    Ph  Np  --  --  Mce                                                                              Σ4                                                                        C.sub.2 H.sub.5                            89                                                                              C.sub.11 H.sub.23                                                                         Ph  Np  --  --  Mod                                                                              Σ4                                                                        C.sub.6 H.sub.13                           90                                                                              C.sub.5 H.sub.11                                                                          Py1 Ep1 --  --  Om Σ4                                                                        C.sub.5 H.sub.11                           91                                                                              C.sub.8 H.sub.17 OC.sub.2 H.sub.4                                                         Ph  Ep1 --  --  Om Σ4                                                                        C.sub.5 H.sub.11                           92                                                                              C.sub.6 H.sub.13                                                                          Ph  Ep1 --  --  Em Σ4                                                                        C.sub.8 H.sub.17                           93                                                                              C.sub.9 H.sub.19                                                                          Py1 Gp1 --  --  Om Σ4                                                                        C.sub.5 H.sub.11                           94                                                                              C.sub.8 H.sub.17                                                                          Ph  Gp1 --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           95                                                                              C.sub.3 H.sub.7 COO                                                                       Ph  Gp1 --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           96                                                                              C.sub.4 H.sub.9                                                                           Ph  Id1 --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           97                                                                              C.sub.12 H.sub.25                                                                         Ph  Io1 --  --  Em Σ4                                                                        C.sub.6 H.sub.13                           98                                                                              C.sub.10 H.sub.21                                                                         Ph  Cm1 --  --  Om Σ4                                                                        C.sub.8 H.sub.17                           99                                                                              C.sub.6 H.sub.13                                                                          Ph  Ph  --  --  Em Σ4                                                                        C.sub.8 H.sub.17                          100                                                                              C.sub.3 H.sub.7                                                                           Ph  --  OCH.sub.2                                                                         Py1 Om Σ4                                                                        C.sub.2 H.sub.5                           101                                                                              C.sub.4 H.sub.9                                                                           Ph2CN                                                                             Ph  --  Pr1 Om Σ4                                                                        C.sub.10 H.sub.21                         102                                                                              C.sub.5 H.sub.11                                                                          Ph  Ph3F                                                                              OCH.sub.2                                                                         Tz1 Em Σ4                                                                        C.sub.6 H.sub.13                          103                                                                              C.sub.6 H.sub.13                                                                          Ph  Ph  OCO Tn  Om Σ4                                                                        C.sub.8 H.sub.17                          104                                                                              C.sub.7 H.sub.15                                                                          Tn  Ph  --  Py1 Od Σ4                                                                        C.sub.8 H.sub.17                          105                                                                              C.sub.10 H.sub.21                                                                         Ph  Ph  --  Cy1 Em Σ4                                                                        C.sub.5 H.sub.11                          __________________________________________________________________________

The optically active compound (b) may particularly preferably berepresented by the formula (IV) wherein R⁴² is a linear or branchedalkyl or alkoxy group having 1-18 carbon atoms; R⁴³ is a linear orbranched alkyl group having 1-10 carbon atoms; m42 is 0; A⁴² is ;##STR15## A⁴³ is; ##STR16## and X⁴³ is --O--, --OCH₂ --, --COO--,--COOCH₂ CH₂ -- or --OCH₂ CH₂ --. Such a compound (b) is effective inallowing a low viscosity and a wide temperature range showing a chiralsmectic phase to the resultant liquid crystal composition due to itsphenyl-pyrimidine skeleton.

Compound (b) of the formula (V) ##STR17## in which R₅₂ is a linear orbranched alkyl group having 1-18 carbon atoms capable of including atleast one --CH₂ -- group which can be replaced by --Y⁵ --, --Y⁵ --CO--,--CO--Y⁵ --, --CO--, --OCOO--, --CH═CH-- or --C.tbd.C-- wherein Y⁵ is Oor S;

R⁵³ is a linear or branched alkyl or alkoxy group having 1-10 carbonatoms;

m52 is 0, 1 or 2;

A⁵², A⁵³ and A⁵⁴ each may have one or two substituents comprising F, Cl,Br, CH₃, CF₃ and/or CN and independently denote a single bond1,4-phenylene; pyridine-2,5-diyl pyrimidine-2,5-diyl; pyrazine-2,5-diyl;pyridazine-3,6-diyl; 1,4-cyclohexylene; 1,3-dioxane-2,5-diyl;1,3-dithiane-2,5-diyl; thiophene-2,5-diyl; thiazole-2,5-diyl;thiadiazole-2,5-diyl; benzoxazole-2,5-diyl; benzoxazole-2,6-diyl;benzothiazole-2,5-diyl; benzothiazole-2,6-diyl; benzofuran-2,5-diyl;benzofuran-2,6-diyl; quinoxaline-2,6-diyl; quinoline-2,6-diyl;2,6-naphthylene; indan-2,5-diyl; 2-alkylindan-2,5-diyl having a linearor branched alkyl group having 1-18 carbon atom; indanone-2,6-diyl;2-alkylindanone-2,6-diyl having a linear or branched alkyl group having1-18 carbon atoms; coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl havinga linear or branched alkyl group having 1-18 carbon atoms;

X⁵² is a single bond, --COO--, --OCO--, --CH₂ O-- or --OCH₂ --;

X⁵³ is a single bond, --CO-- or --CH₂ -- when L52 is 0, or X⁵³ is asingle bond or --CH₂ -- when L52 is 1;

L52 and L53 are 0 or 1; and

C, is an asymmetric carbon atom.

Examples of the compound (b) of the formula (V) may include those asdescribed in JP-A Nos. 61-293288 and 63-44551. The compound (b) of theformula (V) may be produced through processes as described in thesedocuments.

Specific and preferred examples of the optically active compound (b) ofthe formula (V) may include those represented by the followingstructural formulae (Ex. Comp. Nos. 5-1 to 5-105 indicated as Nos. 1-105in Table 3 below) including abbreviations used for the respective groupslisted below in addition to those listed for Table 1. In Table 3, thestructural formula (Ex. Comp. No. 5-59 indicated as No. 59) has m52being 2. ##STR18##

                                      TABLE 3                                     __________________________________________________________________________    No.                                                                              R.sup.52    A.sup.52                                                                          A.sup.53                                                                          X.sup.52                                                                            A.sup.54                                                                          X.sup.53                                                                           Σ5                                                                         R.sup.53                             __________________________________________________________________________     1 C.sub.6 H.sub.13                                                                          Ph  Ph  --    --  --   Σ51                                                                        C.sub.8 H.sub.17                      2 C.sub.8 H.sub.17 O                                                                        Ph  Ph  --    --  --   Σ53                                                                        C.sub.8 H.sub.17                      3 C.sub.5 H.sub.11 O                                                                        Ph  Ph2F                                                                              --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      4 CH.sub.3 O  Ph  Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      5 C.sub.6 H.sub.13 CH(CH.sub.3)(CH.sub.2).sub.2 O                                           Ph  Ph  --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      6 C.sub.7 H.sub.15 O                                                                        Ph  P23F                                                                              --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      7 C.sub.6 H.sub.13                                                                          Ph  Ph  --    --  CO   Σ51                                                                        C.sub.9 H.sub.19                      8 C.sub.7 H.sub.15 O                                                                        Ph  Ph  --    --  CO   Σ53                                                                        C.sub.5 H.sub.11                      9 C.sub.8 H.sub.17 O                                                                        Ph  Ph  --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      10                                                                              C.sub.8 H.sub.17                                                                          Pr1 Ph  --    --  --   Σ53                                                                        C.sub.8 H.sub.17                      11                                                                              C.sub.10 H.sub.21                                                                         Pr2 Ph  --    --  --   Σ51                                                                        C.sub.4 H.sub.9                       12                                                                              C.sub.11 H.sub.23                                                                         Pr2 Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      13                                                                              C.sub.12 H.sub.25                                                                         Pr2 Ph  --    --  --   Σ51                                                                        C.sub.8 H.sub.17                      14                                                                              C.sub.4 H.sub.9 O                                                                         Py1 Ph  --    --  --   Σ51                                                                        C.sub.10 H.sub.21                     15                                                                              C.sub.13 H.sub.27                                                                         Py2 Ph  --    --  --   Σ53                                                                        C.sub.5 H.sub.11                      16                                                                              C.sub.7 H.sub.15                                                                          Py2 Ph  --    --  --   Σ52                                                                        OC.sub.5 H.sub.11                     17                                                                              C.sub.6 H.sub.13 CH(CH.sub.3)CH.sub.2 O                                                   Py2 Ph  --    --  --   Σ51                                                                        C.sub.9 H.sub.19                      18                                                                              C.sub.5 H.sub.11 O                                                                        Py2 P23F                                                                              --    --  --   Σ52                                                                        C.sub.4 H.sub.9                       19                                                                              C.sub.10 H.sub.21                                                                         Py2 Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      20                                                                              C.sub.8 H.sub.17                                                                          Py2 Ph3F                                                                              --    --  --   Σ51                                                                        C.sub.8 H.sub.17                      21                                                                              C.sub.6 H.sub.13                                                                          Cy  Ph  --    --  --   Σ52                                                                        OC.sub.4 H.sub.9                      22                                                                              C.sub.3 H.sub.7                                                                           Cy  Ph  --    --  CH.sub.2                                                                           Σ53                                                                        C.sub.5 H.sub.11                      23                                                                              C.sub.5 H.sub.11                                                                          Cy  Ph  --    --  --   Σ51                                                                        C.sub.4 H.sub.9                       24                                                                              C.sub.10 H.sub.21                                                                         Cy  Ph  --    --  CO   Σ53                                                                        C.sub.10 H.sub.21                     25                                                                              C.sub.6 H.sub.13                                                                          Pa  Ph  --    --  --   Σ53                                                                        C.sub.10 H.sub.21                     26                                                                              C.sub.7 H.sub.15 OCO                                                                      Pd  Ph  --    --  --   Σ51                                                                        C.sub.3 H.sub.7                       27                                                                              C.sub.6 H.sub.13                                                                          Dt2 Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      28                                                                              C.sub.8 H.sub.17                                                                          Tn  Ph  --    --  --   Σ53                                                                        C.sub.9 H.sub.19                      29                                                                              C.sub.5 H.sub.11                                                                          Tz1 Ph  --    --  --   Σ51                                                                        C.sub.9 H.sub.19                      30                                                                              C.sub.9 H.sub.19 O                                                                        Tz2 Ph  --    --  --   Σ52                                                                        C.sub.6 H.sub.13                      31                                                                              C.sub.2 H.sub.5                                                                           Td  Ph  --    --  --   Σ51                                                                        C.sub.7 H.sub.15                      32                                                                              C.sub.10 H.sub.21                                                                         Dx2 Ph  --    --  --   Σ51                                                                        C.sub.8 H.sub.17                      33                                                                              C.sub.6 H.sub.13                                                                          Boa2                                                                              Ph  --    --  --   Σ52                                                                        OC.sub.10 H.sub.21                    34                                                                              C.sub.15 H.sub.31                                                                         Bob2                                                                              Ph  --    --  --   Σ53                                                                        C.sub.10 H.sub.21                     35                                                                              C.sub.7 H.sub.15                                                                          Bta2                                                                              Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      36                                                                              C.sub.16 H.sub.33 O                                                                       Btb2                                                                              Ph  --    --  --   Σ53                                                                        C.sub.9 H.sub.19                      37                                                                              C.sub.6 H.sub.13                                                                          Np  Ph  --    --  CO   Σ53                                                                        C.sub.6 H.sub.13                      38                                                                              C.sub.5 H.sub.11                                                                          Np  Ph  --    --  --   Σ51                                                                        C.sub.4 H.sub.9                       39                                                                              C.sub.8 H.sub.17 CH(CH.sub.3)CH.sub.2 O                                                   Ep1 Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      40                                                                              C.sub.4 H.sub.9                                                                           Ep2 Ph  --    --  CH.sub.2                                                                           Σ51                                                                        C.sub.8 H.sub.17                      41                                                                              C.sub.6 H.sub.13                                                                          Gp1 Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      42                                                                              C.sub.7 H.sub.15                                                                          Gp2 Ph  --    --  --   Σ51                                                                        C.sub.2 H.sub.5                       43                                                                              C.sub.6 H.sub.13                                                                          Cm1 Ph  --    --  --   Σ53                                                                        C.sub.10 H.sub.21                     44                                                                              C.sub.8 H.sub.17                                                                          Io1 Ph  --    --  --   Σ53                                                                        C.sub.2 H.sub.5                       45                                                                              C.sub.18 H.sub.37                                                                         Id1 Ph  --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      46                                                                              C.sub.11 H.sub.23                                                                         Id1 Ph  --    --  --   Σ51                                                                        C.sub.5 H.sub.11                      47                                                                              C.sub.8 H.sub.17                                                                          Id1 Ph  --    --  --   Σ52                                                                        C.sub.5 H.sub.11                      48                                                                              C.sub.5 H.sub.11                                                                          Id1 Ph2F                                                                              --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      49                                                                              C.sub.6 H.sub.13                                                                          Tn  Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      50                                                                              C.sub.4 H.sub.9 O                                                                         Tz2 Ph  --    --  --   Σ53                                                                        C.sub.8 H.sub.17                      51                                                                              C.sub.12 H.sub.25                                                                         Btb2                                                                              Ph  --    --  --   Σ53                                                                        C.sub.10 H.sub.21                     52                                                                              C.sub.6 H.sub.13 O                                                                        Btb2                                                                              Ph  --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      53                                                                              CH.sub.2CH(CH.sub.2).sub.3 O                                                              Ep2 Ph  --    --  --   Σ52                                                                        C.sub.5 H.sub.11                      54                                                                              C.sub.9 H.sub.19                                                                          Gp2 Ph  --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      55                                                                              C.sub.5 H.sub.11                                                                          Np  Ph  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      56                                                                              C.sub.6 H.sub.13                                                                          Ph  Ph  --    Ph  --   Σ53                                                                        C.sub.6 H.sub.13                      57                                                                              C.sub.8 H.sub.17 COO                                                                      Pr2 Ph  --    Ph  --   Σ53                                                                        C.sub.5 H.sub.11                      58                                                                              C.sub.3 H.sub.7                                                                           Py2 Ph  --    Ph  --   Σ53                                                                        C.sub.4 H.sub.9                       59                                                                              C.sub.5 H.sub.11                                                                          --  Ha2 COO   Ph  --   Σ51                                                                        C.sub.4 H.sub.9                       60                                                                              C.sub.6 H.sub.13                                                                          Ph  Py2 COO   Ph  --   Σ51                                                                        C.sub.6 H.sub.13                      61                                                                              C.sub.9 H.sub.19                                                                          Ph  Py1 --    Ph  --   Σ52                                                                        C.sub.6 H.sub.13                      62                                                                              C.sub.13 H.sub.27                                                                         Ph  Cy  --    P3Br                                                                              --   Σ53                                                                        C.sub.5 H.sub.11                      63                                                                              C.sub.10 H.sub.21 O                                                                       Ph  Py1 --    Ph  --   Σ53                                                                        C.sub.6 H.sub.13                      64                                                                              C.sub.7 H.sub.15                                                                          Ph  Py2 OCH.sub.2                                                                           Ph  --   Σ53                                                                        C.sub.5 H.sub.11                      65                                                                              C.sub.4 H.sub.9                                                                           Ph3TF                                                                             Pa  COO   Ph  --   Σ53                                                                        C.sub.6 H.sub.13                      66                                                                              CH.sub.3    Hb2 Ph  --    --  --   Σ53                                                                        C.sub.8 H.sub.17                      67                                                                              C.sub.8 H.sub.17                                                                          Ph  Tn  --    Ph  --   Σ52                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub                                             .2                                    68                                                                              C.sub.2 H.sub.5                                                                           Ph  Tz1 --    Ph2M                                                                              --   Σ51                                                                        C.sub.8 H.sub.17                      69                                                                              C.sub.6 H.sub.13                                                                          --  Ph  COO   Ph  --   Σ51                                                                        C.sub.8 H.sub.17                      70                                                                              C.sub.10 H.sub.21                                                                         Ph  Td  --    Ph  --   Σ51                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub                                             .2                                    71                                                                              C.sub.10 H.sub.21                                                                         Ph  Py1 --    --  --   Σ52                                                                        C.sub.6 H.sub.13                      72                                                                              C.sub.6 H.sub.13                                                                          Ph  Py1 --    --  --   Σ53                                                                        C.sub.4 H.sub.9                       73                                                                              C.sub.6 H.sub.13 OCO                                                                      Ph  Py1 --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      74                                                                              C.sub.7 H.sub.15                                                                          Ph  Pr2 --    --  --   Σ53                                                                        C.sub.5 H.sub.11                      75                                                                              C.sub.9 H.sub.19                                                                          Ph  Pr2 --    --  --   Σ53                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub                                             .2                                    76                                                                              C.sub.7 H.sub.15                                                                          Ph  Pr2 --    --  --   Σ51                                                                        C.sub.6 H.sub.13                      77                                                                              C.sub.5 H.sub.11 O                                                                        Py2 Cy  --    --  --   Σ51                                                                        C.sub.10 H.sub.21                     78                                                                              C.sub.4 H.sub.9                                                                           Ph  Cy  --    --  --   Σ53                                                                        C.sub.2 H.sub.5                       79                                                                              C.sub.12 H.sub.25                                                                         Ph  Cy  --    --  --   Σ52                                                                        C.sub.5 H.sub.11                      80                                                                              C.sub.6 H.sub.13 CC                                                                       Ph  Pa  --    --  --   Σ51                                                                        C.sub.10 H.sub.21                     81                                                                              C.sub.8 H.sub.17 O                                                                        Ph  Pd  --    --  --   Σ52                                                                        C.sub.6 H.sub.13                      82                                                                              C.sub.3 H.sub.7                                                                           Ph2Cl                                                                             Tn  --    --  --   Σ52                                                                        C.sub.10 H.sub.21                     83                                                                              C.sub.4 H.sub.9                                                                           Ph  Tn  --    --  --   Σ53                                                                        C.sub.8 H.sub.17                      84                                                                              C.sub.8 H.sub.17                                                                          Ph  Tz1 --    --  --   Σ53                                                                        C.sub.8 H.sub.17                      85                                                                              C.sub.4 H.sub.9 OCH(CH.sub.3)COO                                                          Ph  Tz1 --    --  --   Σ51                                                                        C.sub.7 H.sub.15                      86                                                                              C.sub.6 H.sub.13                                                                          Ph2F                                                                              Td  --    --  --   Σ53                                                                        (CH.sub.2).sub.3 CH(CH.sub.3)C.su                                             b.6 H.sub.13                          87                                                                              C.sub.5 H.sub.11                                                                          Py2 Np  --    --  --   Σ51                                                                        C.sub.9 H.sub.19                      88                                                                              CH.sub.3    Ph  Np  --    --  --   Σ53                                                                        C.sub.2 H.sub.5                       89                                                                              C.sub.11 H.sub.23                                                                         Ph  Np  --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      90                                                                              C.sub.5 H.sub.11                                                                          Py1 Ep1 --    --  --   Σ53                                                                        C.sub.5 H.sub.11                      91                                                                              C.sub.8 H.sub.17 OC.sub.2 H.sub.4                                                         Ph  Ep1 --    --  --   Σ53                                                                        C.sub.5 H.sub.11                      92                                                                              C.sub.6 H.sub.13                                                                          Ph  Ep1 --    --  --   Σ51                                                                        C.sub.8 H.sub.17                      93                                                                              C.sub.9 H.sub.19                                                                          Py1 Gp1 --    --  --   Σ53                                                                        C.sub.5 H.sub.11                      94                                                                              C.sub.8 H.sub.17                                                                          Ph  Gp1 --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      95                                                                              C.sub.3 H.sub.7 COO                                                                       Ph  Gp1 --    --  --   Σ53                                                                        C.sub.8 H.sub.17                      96                                                                              C.sub.4 H.sub.9                                                                           Ph  Id1 --    --  --   Σ51                                                                        C.sub.8 H.sub.17                      97                                                                              C.sub.12 H.sub.25                                                                         Ph  Io1 --    --  --   Σ53                                                                        C.sub.6 H.sub.13                      98                                                                              C.sub.10 H.sub.21                                                                         Ph  Cm1 --    --  --   Σ52                                                                        C.sub.8 H.sub.17                      99                                                                              C.sub.6 H.sub.13                                                                          Ph  Ph  --    --  --   Σ53                                                                        C.sub.8 H.sub.17                     100                                                                              C.sub.3 H.sub.7                                                                           Ph  Ph  OCH.sub.2                                                                           Py1 --   Σ53                                                                        C.sub.2 H.sub.5                      101                                                                              C.sub.4 H.sub.9                                                                           Ph2CN                                                                             Ph  --    Pr1 --   Σ51                                                                        C.sub.10 H.sub.21                    102                                                                              C.sub.5 H.sub.11                                                                          Ph  Ph3F                                                                              OCH.sub.2                                                                           Tz1 --   Σ53                                                                        C.sub.6 H.sub.13                     103                                                                              C.sub.6 H.sub.13                                                                          Ph  Ph  --    Tn  --   Σ51                                                                        C.sub.8 H.sub.17                     104                                                                              C.sub.7 H.sub.15                                                                          Tn  Ph  --    Py1 --   Σ52                                                                        C.sub.8 H.sub.17                     105                                                                              C.sub.10 H.sub.21                                                                         Ph  Ph  --    Cy1 --   Σ53                                                                        C.sub.5 H.sub.11                     __________________________________________________________________________

The above-mentioned optically active compound (b) of the formula (V) isexcellent in mesomorphism, spontaneous polarization and a solubilitywith the fluorine-containing mesomorphic compound (a) due to itsparticular structure. Further, the compound (b) of the formula (V) hasthe advantage of effectively controlling a helical pitch or thedirection of the helix affecting an alignment characteristic resultingfrom various structures of a chiral portion readily modified. The aboveadvantages (e.g., a large spontaneous polarization and a control ofhelical pitch or the direction of helix) can also be realized by usingtwo or more species of the compound (b) of the formula (V).

The optically active compound (b) may particularly preferably berepresented by the formula (V) wherein R⁵² is a linear or branched alkylor alkoxy group having 1-18 carbon atoms; R⁵³ is a linear or branchedalkyl group having 1-10 carbon atoms; m52 and L52 are 0; A⁵² is##STR19## A⁵³ is ##STR20## and X⁵³ is a single bond or --CO--. Such acompound (b) is effective in allowing a low viscosity and a widetemperature range showing a chiral smectic phase to the resultant liquidcrystal composition due to its phenyl-pyrimidine skeleton.

Compound (b) of the formula (VI)

    R.sup.62 --(A.sup.62 --X.sup.62).sub.m62 --A.sup.63 --A.sup.64 --X.sup.63 --R.sup.63                                                (VI),

in which

R⁶² and R⁶³ independently denote a linear or branched alkyl group having1-18 carbon atoms and at least one asymmetric carbon atom directlyconnected with F, CF₃ or CH₃ and capable of including at least one --CH₂-- group which can be replaced by wherein Y⁶ is O or S;

m62 is 0, 1 or 2;

A⁶², A⁶³ and A⁶⁴ each may have one or two substituents comprising F, Cl,Br, CH₃, CF₃ and/or CN and independently denote a single bond;1,4-phenylene; pyridine-2,5-diyl; pyrimidine-2,5-diyl;pyrazine-2,5-diyl; pyridazine-3,6-diyl; 1,4-cyclohexylene; 1,3-dioxane-2,5-diyl; 1,3-dithiane-2,5-diyl; thiophene-2,5-diyl;thiazole-2,5-diyl; thiadiazole-2,5-diyl; benzoxazole-2,5-diyl;benzoxazole-2,6-diyl; benzothiazole-2,5-diyl; benzothiazole-2,6-diyl;benzofuran-2,5-diyl; benzofuran-2,6-diyl; quinoxaline-2,6-diyl;quinoline-2,6-diyl; 2,6-naphthylene; indan-2,5-diyl:2-alkylindan-2,5-diyl having a linear or branched alkyl group having1-18 carbon atom; indanone-2,6-diyl; 2-alkylindanone-2,6-diyl having alinear or branched alkyl group having 1-18 carbon atoms;coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl having a linear orbranched alkyl group having 1-18 carbon atoms; and

X⁶² and X⁶³ independently denote a single bond, --COO--, --OCO--, --CH₂O-- or --OCH₂ --.

Examples of the compound (b) of the formula (VI) may include those asdescribed in JP-A Nos. 6-234749. The compound (b) of the formula (VI)may be produced through a process as described in the documents.

Specific and preferred examples of the optically active compound (b) ofthe formula (VI) may include those represented by the followingstructural formulae (Ex. Comp. Nos. 6-1 to 6-105 indicated as Nos. 1-105in Table 4 below) including abbreviations used for the respective groupslisted below in addition to those listed for Table 1. In Table 4, thestructural formula (Ex. Comp. No. 6-67 indicated as No. 67) has m62being 2. In the formula (VI), R⁶² -corresponds to R^(62') --ψ(any one ofψ¹ to ψ⁷)-- and --R⁶³ corresponds to --Σ6 (any one of Σ61 toΣ65)--R^(63') indicated in Table 4. ##STR21##

                                      TABLE 4                                     __________________________________________________________________________    R.sup.62 --(A.sup.62 --X.sup.62).sub.m62 --A.sup.63 --A.sup.64 --X.sup.63     --R.sup.63                                       (VI)                         No.                                                                              R.sup.62 ' Ψ                                                                           A.sup.62                                                                          X.sup.62                                                                          A.sup.63                                                                          A.sup.64                                                                          X.sup.65                                                                            Σ6                                                                         R.sup.63'                            __________________________________________________________________________     1 C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Ph  Ph  --O-- Σ61                                                                        C.sub.8 H.sub.17                      2 C.sub.8 H.sub.17 O                                                                       Ψ.sup.3                                                                     --  --  Ph  Ph  --COO--                                                                             Σ61                                                                        C.sub.18 H.sub.37                     3 C.sub.5 H.sub.11 O                                                                       Ψ.sup.3                                                                     --  --  Ph  Ph2F                                                                              --O-- Σ61                                                                        C.sub.6 H.sub.13                      4 CH.sub.3 O Ψ.sup.3                                                                     --  --  Ph  Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      5 C.sub.6 H.sub.13 CH(CH.sub.3)                                                            Ψ.sup.1                                                                     --  --  Ph  Ph  --COO--                                                                             Σ61                                                                        C.sub.6 H.sub.13                      6 C.sub.7 H.sub.15                                                                         Ψ.sup.2                                                                     --  --  Ph  Ph23F                                                                             --O-- Σ61                                                                        C.sub.6 H.sub.13                      7 C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Ph  Ph  --O-- Σ61                                                                        C.sub.9 H.sub.19                      8 C.sub.7 H.sub.15 O                                                                       Ψ.sup.3                                                                     --  --  Ph  Ph  --O-- Σ61                                                                        C.sub.5 H.sub.11                      9 C.sub.8 H.sub.17                                                                         Ψ.sup.1                                                                     --  --  Ph  Ph  --O-- Σ64                                                                        C.sub.6 H.sub.13                      10                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.4                                                                     --  --  Pr1 Ph  --O-- Σ61                                                                        C.sub.8 H.sub.17                      11                                                                              C.sub.10 H.sub.21                                                                        Ψ.sup.1                                                                     --  --  Pr2 Ph  --O-- Σ61                                                                        C.sub.4 H.sub.9                       12                                                                              C.sub.11 H.sub.23                                                                        Ψ.sup.1                                                                     --  --  Pr2 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      13                                                                              C.sub.12 H.sub.25                                                                        Ψ.sup.1                                                                     --  --  Pr2 Ph  --O-- Σ62                                                                        C.sub.8 H.sub.17                      14                                                                              C.sub.4 H.sub.9 O                                                                        Ψ.sup.3                                                                     --  --  Py1 Ph  --O-- Σ61                                                                        C.sub.10 H.sub.21                     15                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Py2 Ph  --O-- Σ61                                                                        C.sub.8 H.sub.17                      16                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Py2 Ph  --OCO--                                                                             Σ61                                                                        C.sub.8 H.sub.17                      17                                                                              C.sub.6 H.sub.13 CH(CH.sub.3)CH.sub.2 O                                                  Ψ.sup.4                                                                     --  --  Py2 Ph  --OCO--                                                                             Σ61                                                                        C.sub.9 H.sub.19                      18                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.1                                                                     --  --  Py2 Ph23F                                                                             --OCO--                                                                             Σ63                                                                        C.sub.4 H.sub.9                       19                                                                              C.sub.2 H.sub.5                                                                          Ψ.sup.7                                                                     --  --  Py2 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      20                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.2                                                                     --  --  Py2 Ph3F                                                                              --COO--                                                                             Σ64                                                                        C.sub.8 H.sub.17                      21                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Cy  Ph  --O-- Σ61                                                                        C.sub.4 H.sub.9                       22                                                                              C.sub.3 H.sub.7                                                                          Ψ.sup.1                                                                     --  --  Cy  Ph  --COO--                                                                             Σ62                                                                        C.sub.5 H.sub.11                      23                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.2                                                                     --  --  Cy  Ph  --O-- Σ61                                                                        C.sub.14 H.sub.29                     24                                                                              C.sub.10 H.sub.21                                                                        Ψ.sup.2                                                                     --  --  Cy  Ph  --O-- Σ61                                                                        C.sub.10 H.sub.21                     25                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Pa  Ph  --O-- Σ62                                                                        C.sub.10 H.sub.21                     26                                                                              C.sub.7 H.sub.15 OCO                                                                     Ψ.sup.5                                                                     --  --  Pd  Ph  --O-- Σ61                                                                        C.sub.3 H.sub.7                       27                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Dt2 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      28                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.1                                                                     --  --  Tn  Ph  --O-- Σ61                                                                        C.sub.9 H.sub.19                      29                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.2                                                                     --  --  Tz1 Ph  --O-- Σ61                                                                        C.sub.9 H.sub.19                      30                                                                              C.sub.9 H.sub.19 O                                                                       Ψ.sup.3                                                                     --  --  Tz2 Ph  --COO--                                                                             Σ61                                                                        C.sub.6 H.sub.13                      31                                                                              C.sub.2 H.sub.5                                                                          Ψ.sup.1                                                                     --  --  Td  Ph  --O-- Σ61                                                                        C.sub.7 H.sub.15                      32                                                                              C.sub.10 H.sub.21                                                                        Ψ.sup.2                                                                     --  --  Dx2 Ph  --OCO--                                                                             Σ63                                                                        C.sub.8 H.sub.17                      33                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Boa2                                                                              Ph  --O-- Σ61                                                                        C.sub.10 H.sub.21                     34                                                                              C.sub.15 H.sub.31                                                                        Ψ.sup.1                                                                     --  --  Bob2                                                                              Ph  --O-- Σ61                                                                        C.sub.10 H.sub.21                     35                                                                              C.sub.7 H.sub.15                                                                         Ψ.sup.1                                                                     --  --  Bta2                                                                              Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      36                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.6                                                                     --  --  Btb2                                                                              Ph    --  Σ65                                                                        C.sub.6 H.sub.13                      37                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Np  Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      38                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.1                                                                     --  --  Np  Ph  --COO--                                                                             Σ61                                                                        C.sub.4 H.sub.9                       39                                                                              C.sub.8 H.sub.17 CH(CH.sub.3)CH.sub.2                                                    Ψ.sup.2                                                                     --  --  Ep1 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      40                                                                              C.sub.4 H.sub.9                                                                          Ψ.sup.1                                                                     --  --  Ep2 Ph  --O-- Σ61                                                                        C.sub.8 H.sub.17                      41                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.2                                                                     --  --  Gp1 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      42                                                                              C.sub.7 H.sub.15                                                                         Ψ.sup.1                                                                     --  --  Gp2 Ph  --O-- Σ61                                                                        C.sub.12 H.sub.25                     43                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Cm1 Ph  --O-- Σ61                                                                        C.sub.10 H.sub.21                     44                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.1                                                                     --  --  Io1 Ph  --O-- Σ61                                                                        C.sub.12 H.sub.25                     45                                                                              C.sub.12 H.sub.25                                                                        Ψ.sup.1                                                                     --  --  Id1 Ph  --COO--                                                                             Σ61                                                                        C.sub.6 H.sub.13                      46                                                                              C.sub.11 H.sub.23                                                                        Ψ.sup.1                                                                     --  --  Id1 Ph  --OCO--                                                                             Σ63                                                                        C.sub.5 H.sub.11                      47                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.1                                                                     --  --  Id1 Ph  --O-- Σ61                                                                        C.sub.5 H.sub.11                      48                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.2                                                                     --  --  Id1 Ph2F                                                                              --COO--                                                                             Σ61                                                                        C.sub.6 H.sub.13                      49                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Tn  Ph  --COO--                                                                             Σ64                                                                        C.sub.6 H.sub.13                      50                                                                              C.sub.4 H.sub.9 O                                                                        Ψ.sup.3                                                                     --  --  Tz2 Ph  --O-- Σ61                                                                        C.sub.8 H.sub.17                      51                                                                              C.sub.12 H.sub.25                                                                        Ψ.sup.1                                                                     --  --  Btb2                                                                              Ph  --O-- Σ62                                                                        C.sub.10 H.sub.21                     52                                                                              C.sub.6 H.sub.13 O                                                                       Ψ.sup.1                                                                     --  --  Btb2                                                                              Ph  --O-- Σ62                                                                        C.sub.6 H.sub.13                      53                                                                              CH.sub.2 ═CH(CH.sub.2).sub.3 O                                                       Ψ.sup.3                                                                     --  --  Ep2 Ph  --O-- Σ61                                                                        C.sub.5 H.sub.11                      54                                                                              C.sub.9 H.sub.19                                                                         Ψ.sup.4                                                                     --  --  Gp2 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      55                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.4                                                                     --  --  Np  Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      56                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     Ph  OCO Ph  Ph  --O-- Σ62                                                                        C.sub.6 H.sub.13                      57                                                                              C.sub.8 H.sub.17 COO                                                                     Ψ.sup.2                                                                     Pr2 --  Ph  Ph  --COO--                                                                             Σ61                                                                        C.sub.5 H.sub.11                      58                                                                              C.sub.3 H.sub.7                                                                          Ψ.sup.1                                                                     Py2 --  Ph  Ph  --COO--                                                                             Σ64                                                                        C.sub.4 H.sub.9                       59                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.1                                                                     --  --  Ha2 Ph  --OCO--                                                                             Σ63                                                                        C.sub.4 H.sub.9                       60                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     Ph  COO Pr2 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      61                                                                              C.sub.9 H.sub.19                                                                         Ψ.sup.1                                                                     Ph  --  Pr1 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      62                                                                              C.sub.13 H.sub.27                                                                        Ψ.sup.1                                                                     Ph  --  Cy  Ph3Br                                                                             --O-- Σ61                                                                        C.sub.5 H.sub.11                      63                                                                              C.sub.10 H.sub.21 O                                                                      Ψ.sup.1                                                                     Ph  COO Py1 Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      64                                                                              C.sub.7 H.sub.15                                                                         Ψ.sup.2                                                                     Ph  COO Py2 Ph  --O-- Σ61                                                                        C.sub.5 H.sub.11                      65                                                                              C.sub.4 H.sub.9                                                                          Ψ.sup.1                                                                     Ph3T                                                                              COO Pa  Ph  --O-- Σ61                                                                        C.sub.6 H.sub.13                      66                                                                              CH.sub.3   Ψ.sup.1                                                                     --  --  Hb2 Ph  --O-- Σ62                                                                        C.sub.8 H.sub.17                      67                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.1                                                                     Ph  COO Tn  Ph  --O-- Σ62                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub                                             .2                                    68                                                                              C.sub.2 H.sub.5                                                                          Ψ.sup.1                                                                     Ph  --  Tz1 Ph2M                                                                              --O-- Σ61                                                                        C.sub.8 H.sub.17                      69                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.2                                                                     Ph  COO Ph  --  --O-- Σ61                                                                        C.sub.8 H.sub.17                      70                                                                              C.sub.10 H.sub.21                                                                        Ψ.sup.1                                                                     Ph  --  Td  Ph  --O-- Σ61                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub                                             .2                                    71                                                                              C.sub.10 H.sub.21                                                                        Ψ.sup.1                                                                     --  --  Ph  Py1 --O-- Σ61                                                                        C.sub.6 H.sub.13                      72                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Ph  Py1 --O-- Σ61                                                                        C.sub.4 H.sub.9                       73                                                                              C.sub.6 H.sub.13 OCO                                                                     Ψ.sup.5                                                                     --  --  Ph  Py1 --O-- Σ61                                                                        C.sub.6 H.sub.13                      74                                                                              C.sub.7 H.sub.15                                                                         Ψ.sup.4                                                                     --  --  Ph  Pr2 --O-- Σ61                                                                        C.sub.5 H.sub.11                      75                                                                              C.sub.9 H.sub.19                                                                         Ψ.sup.1                                                                     --  --  Ph  Pr2 --O-- Σ61                                                                        (CH.sub.2).sub.3 CH(CH.sub.3).sub                                             .2                                    76                                                                              C.sub.7 H.sub.15                                                                         Ψ.sup.1                                                                     --  --  Ph  Pr2 --O-- Σ61                                                                        C.sub.6 H.sub.13                      77                                                                              C.sub.5 H.sub.11 O                                                                       Ψ.sup.3                                                                     --  --  Py2 Cy  --COO--                                                                             Σ61                                                                        C.sub.10 H.sub.21                     78                                                                              C.sub.4 H.sub.9                                                                          Ψ.sup.1                                                                     --  --  Ph  Cy  --OCO--                                                                             Σ62                                                                        C.sub.12 H.sub.25                     79                                                                              C.sub.12 H.sub.25                                                                        Ψ.sup.1                                                                     --  --  Ph  Cy  --O-- Σ61                                                                        C.sub.5 H.sub.11                      80                                                                              C.sub.6 H.sub.13 C.tbd.C                                                                 Ψ.sup.2                                                                     --  --  Ph  Pa  --COO--                                                                             Σ61                                                                        C.sub.10 H.sub.21                     81                                                                              C.sub.8 H.sub.17 O                                                                       Ψ.sup.3                                                                     --  --  Ph  Pd  --COO--                                                                             Σ62                                                                        C.sub.6 H.sub.13                      82                                                                              C.sub.3 H.sub.7                                                                          Ψ.sup.1                                                                     --  --  Ph2Cl                                                                             Tn  --O-- Σ61                                                                        C.sub.10 H.sub.21                     83                                                                              C.sub.4 H.sub.9                                                                          Ψ.sup.1                                                                     --  --  Ph  Tn  --O-- Σ62                                                                        C.sub.8 H.sub.17                      84                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.2                                                                     --  --  Ph  Tz1 --O-- Σ61                                                                        C.sub.8 H.sub.17                      85                                                                              C.sub.4 H.sub.9 OCH(CH.sub.3)COO                                                         Ψ.sup.3                                                                     --  --  Ph  Tz1 --O-- Σ61                                                                        C.sub.7 H.sub.15                      86                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Ph2F                                                                              Td  --O-- Σ64                                                                        (CH.sub.2).sub.3 CH(CH.sub.3)C.su                                             b.6 H.sub.13                          87                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.1                                                                     --  --  Py2 Np  --COO--                                                                             Σ61                                                                        C.sub.9 H.sub.19                      88                                                                              CH.sub.3   Ψ.sup.2                                                                     --  --  Ph  Np  --COO--                                                                             Σ64                                                                        C.sub.12 H.sub.25                     89                                                                              C.sub.11 H.sub.23                                                                        Ψ.sup.1                                                                     --  --  Ph  Np  --O-- Σ62                                                                        C.sub.6 H.sub.13                      90                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.1                                                                     --  --  Py1 Ep1 --O-- Σ61                                                                        C.sub.5 H.sub.11                      91                                                                              C.sub.8 H.sub.17 OC.sub.2 H.sub.4                                                        Ψ.sup.1                                                                     --  --  Ph  Ep1 --O-- Σ62                                                                        C.sub.5 H.sub.11                      92                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Ph  Ep1 --OCO--                                                                             Σ61                                                                        C.sub.8 H.sub.17                      93                                                                              C.sub.9 H.sub.19                                                                         Ψ.sup.1                                                                     --  --  Py1 Gp1 --O-- Σ64                                                                        COOC.sub.5 H.sub.11                   94                                                                              C.sub.8 H.sub.17                                                                         Ψ.sup.1                                                                     --  --  Ph  Gp1 --OCO--                                                                             Σ63                                                                        C.sub.6 H.sub.13                      95                                                                              C.sub.3 H.sub.7 COO                                                                      Ψ.sup.3                                                                     --  --  Ph  Gp1 --O-- Σ61                                                                        C.sub.8 H.sub.17                      96                                                                              C.sub.4 H.sub.9                                                                          Ψ.sup.1                                                                     --  --  Ph  Id1 --O-- Σ61                                                                        C.sub.8 H.sub.17                      97                                                                              C.sub.12 H.sub.25                                                                        Ψ.sup.1                                                                     --  --  Ph  Io1 --O-- Σ61                                                                        C.sub.6 H.sub.13                      98                                                                              C.sub.10 H.sub.21                                                                        Ψ.sup.1                                                                     --  --  Ph  Cm1 --O-- Σ61                                                                        C.sub.8 H.sub.17                      99                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.1                                                                     --  --  Ph  Ph  --O-- Σ64                                                                        C.sub.8 H.sub.17                     100                                                                              C.sub.3 H.sub.7                                                                          Ψ.sup.1                                                                     Ph  OCH.sub.2                                                                         Ph  Py1 --O-- Σ63                                                                        C.sub.12 H.sub.25                    101                                                                              C.sub.4 H.sub.9                                                                          Ψ.sup.1                                                                     Ph2CN                                                                             COO Ph  Pr1 --O-- Σ61                                                                        C.sub.10 H.sub.21                    102                                                                              C.sub.5 H.sub.11                                                                         Ψ.sup.2                                                                     Ph  CH.sub.2 O                                                                        Ph3F                                                                              Tz1 --O-- Σ61                                                                        C.sub.6 H.sub.13                     103                                                                              C.sub.6 H.sub.13                                                                         Ψ.sup.2                                                                     Ph  --  Ph  Tn  --O-- Σ62                                                                        C.sub.8 H.sub.17                     104                                                                              C.sub.7 H.sub.15                                                                         Ψ.sup.1                                                                     Tn  --  Ph  Py1 --O-- Σ61                                                                        C.sub.8 H.sub.17                     105                                                                              C.sub.10 H.sub.21                                                                        Ψ.sup.2                                                                     Ph  --  Ph  Cy1 --O-- Σ61                                                                        C.sub.5 H.sub.11                     __________________________________________________________________________

R⁶³ in the formula (VI) may preferably be represented by the followingformula: ##STR22## in which R⁶⁴ is a linear or branched alkyl grouphaving 1-16 carbon atoms in view of improvements in spontaneouspolarization, viscosity and mutual solubility due to a chiral fluorineportion (--C*H(F)--).

Similarly, R⁶² in the formula (VI) may preferably be represented by thefollowing formula: ##STR23## in which R⁶⁵ is a linear or branched alkylgroup having 1-16 carbon atoms, and d is an integer of 1-6 in view ofimprovements in properties as described in the case of R⁶³.

The optically active compound (b) may particularly preferably berepresented by the formula (VI) wherein m62 is 0; A⁶³ is ##STR24## andA⁶⁴ is ##STR25## Such a compound (b) is effective in allowing a lowviscosity, a mutual solubility of the respective components and a widetemperature range showing a chiral smectic phase to the resultant liquidcrystal composition due to its phenyl-pyrimidine skeleton.

The optically active compound (b) of the formula (VI) is used as aso-called double chiral-type chiral dopant having two chiral centers(which provide a spontaneous polarization) each located in an innerportion of a terminal group, i.e., located on the both sides of acentral core portion. When the double chiral-type chiral dopant (thecompound (b) of the formula (VI)) is used together with the compound (a)having a terminal perfluoroether group or a terminal perfluoroalkylgroup effective in providing a bookshelf structure or a structure havinga small layer inclination angle closer thereto, the resultant liquidcrystal composition shows a good mutual solubility and a largespontaneous polarization to attain good driving characteristics.

The (chiral smectic) liquid crystal composition according to the presentinvention may be obtained by mixing at least one spaces of thefluorine-containing mesomorphic compound (a) (preferably having theformula (I) or (I') with at least one species of the optically activecompound (b) of the formula (II) (preferably of any one of the formulae(III) to (VI)) in an appropriate proportions. The optically activecompound (b) of any one of the formulae (II) to (VI) may generally becontained in the liquid crystal composition in an amount of trace tobelow 50 wt. %, preferably 2-40 wt. %. The optically active compound (b)may also be contained in the liquid crystal composition in a very smallamount (e.g., 1×10⁻⁵ wt. %) so long as it functions as a chiral dopant.If the addition amount of the optically active compound (b) is at least50 wt. %, the resultant liquid crystal composition shows a highviscosity and a narrow chiral smectic temperature range in some cases.

The (chiral smectic) liquid crystal composition of the invention mayfurther contain at least one species of another mesomorphic compoundand/or another chiral dopant each different from those described aboveand also contain additives such as an antioxidant, an ultravioletray-absorbing agent, a colorant and a pigment.

Examples of another mesomorphic compound may include those as describedin Demus et al., Flussige Kristalle in Tabellen II (VEB Deutschev Verlagfur Grundstoffindustrie, Liepzig, 1984).

The liquid crystal device according to the present invention maypreferably be a (chiral smectic) liquid crystal device using theabove-mentioned chiral smectic liquid crystal composition.

Hereinbelow, an embodiment of the liquid crystal device of the presentinvention will be explained with reference to FIG. 1.

FIG. 1 is a schematic sectional view of an embodiment of the liquidcrystal device for explanation of the structure thereof.

Referring to FIG. 1, the liquid crystal device includes a liquid crystallayer 1 comprising a chiral smectic liquid crystal composition disposedbetween a pair of substrates 2 each having thereon a transparentelectrode 3 and an alignment control layer 4. In the present invention,the transparent electrode 3 and/or the alignment control layer may beformed on one of the substrates 2. The substrates 2 are placed orarranged opposite to each other. The periphery of the substrates 2 issealed up with a sealing agent 5. Outside the thus treated substrates 2,a pair of polarizers 6 are disposed so as to modulate incident lightI_(O) from a light source 7 in cooperation with the liquid crystal 1 toprovide modulated light I. The liquid crystal device can be driven bycontrolling (or switching) the alignment (or orientation) direction ofliquid crystal molecules in accordance with image data based on aswitching signal from a signal power supply (not shown), thus effectingdisplay. Accordingly, the liquid crystal device functions as a displaydevice. Further, in case where two transparent electrodes 3 are arrangedin matrix on the pair of substrates, it is possible to perform patterndisplay and pattern exposure, so that the liquid crystal device is usedas a display device for a personal computer, a word processor, etc., oras a light valve for a printer.

The liquid crystal layer 1 may preferably have a thickness of at most 5μm in order to exhibit bistability. The liquid crystal layer 1 may beconstituted by a lot of smectic liquid crystal molecular layers forminga bookshelf structure or a closer structure thereto having a small layerinclination angle. Each of two substrates 2 comprises glass or plasticand is coated with a transparent electrode 3 comprising a film of SnO₂,In₂ O₃, SnO₂ or ITO (indium-tin-oxide) to form an electrode plate.Further thereon, the alignment control layer 4 is formed by applying asolution containing a material for the alignment control layer or byvapor deposition or sputtering of a material for the alignment controllayer. Examples of the material for the alignment control layer 4 mayinclude: an inorganic material, such as silicon monoxide, silicondioxide, aluminum oxide, zirconinm oxide, magnesium fluoride, ceriumoxide, cerium fluoride, silicon nitride, silicon carbide, or boronnitride; and an organic material, such as polyvinyl alcohol, polyimide,polyamide-imide, polyester, polyamide, polyester-imide,polyparaxylylene, polycarbonate, polyvinyl acetal, polyvinyl chloride,polystyrene, cellulose resin, melamine resin, urea resin or acrylicresin. The surface of the thus prepared alignment control layer 4 may besubjected to uniaxial alignment treatment, as desired, e.g., by rubbingthe surface thereof with a fibrous material such as velvet, cloth orpaper. The uniaxial alignment treatment (rubbing treatment) may beperformed to one of the alignment control films 4 so as to effectivelycontrol an alignment state of liquid crystal molecules. The alignmentcontrol layer 4 may be formed by an oblique vapor deposition methodwherein a film of an oxide such as SiO₂ or an nitride is vapor-depositedon the electrode plate(s) from the oblique direction to the electrodeplate. The liquid crystal device of the invention may further comprise ashort circuit-preventing layer for the pair of substrates, such as aninsulating layer, an inorganic material layer and an organic materiallayer other than those for the above-mentioned alignment control layer,if necessary.

In view of ease of formation and a high alignment control ability, thealignment control layer 4 may preferably comprise a polyimide film or apolyamide film, e.g., formed by applying a polyimide precursor solutionor a polyamic acid solution and curing the solution, followed byuniaxial alignment treatment, particularly rubbing treatment of theresultant film. Examples of a polyimide and a polyamide used for formingthe alignment control layer 4 may preferably include those having amolecular structure with a high rigidity, a high linear property and ahigh crystallinity in order to uniformly align the chiral smectic liquidcrystal composition. Such a polyimide and polyamide may preferably berepresented by the following formula (VII) and formula (VIII),respectively.

Formula (VII) ##STR26## in which R₇₁ is ##STR27## R₇₂ and R₇₄independently denote ##STR28## R₇₃ is a single bond or --O--; and 1 is0, 1 or 2.

Formula (VIII)

    (R.sub.81 --R.sub.82 --R.sub.83 --R.sub.84 --(R.sub.85)r.sub.8 R.sub.86)(IX),

in which

R₈₁ is an alkylene group having 1-20 carbon

atoms, ##STR29## R₈₂ and R₈₆ are independently --CONH-- or --NHCO--; R₈₃and R₈₅ are independently ##STR30##

or an alkylene group having 1-20 carbon atoms:

R₈₄ is a single bond or --O--; and

r8 is 0, 1 or 2.

Specific examples of the polyimide of the formula (VII) and thepolyamide of the formula (VIII) may include those having the followingrecurring units shown below. ##STR31##

In the present invention, one of the alignment control layers formed onone substrate may comprise a material therefor which is different fromthat for the other alignment control layer in order to improve analignment characteristic in the case of providing a bookshelf structure.

The liquid crystal device of the present invention may be arranged invarious modes or forms as long as it uses a liquid crystal compositioncontaining the fluorine-containing mesomorphic compound (a) and theoptically active compound (b) as essential components thereby to impartrequired functions.

In the present invention, it is possible to effect a display with betterperformances, such as a high contrast ratio, a high brightness, a largedisplay area and a high definition by using the liquid crystalcomposition or the liquid crystal device as mentioned above. Accordingto an embodiment of the display method according to the presentinvention, it is possible to effect a binary display (black and white(or dark and bright)) each at one pixel by sandwiching a liquid crystalcell (i.e., the liquid crystal device before a pair of polarizer isdisposed) between a pair of polarizer so as to provide one of bistablestates showing the darkest state and then applying an electric field tofind a position so as to provide the other of bistable states showing abright state. It is also possible to effect a multiple display (orgradational display) by using a method wherein plural times of a binary(bright-dark) display are performed at a prescribed interval within acertain period of time or a method wherein a part of one pixel issubjected to switching.

The liquid crystal device according to the present invention can be usedas an active element, particularly an active display element, forvarious liquid crystal apparatus, one embodiment of which is describedbelow.

Based on an arrangement appearing hereinbelow and data format comprisingimage data accompanied with scanning line address data and by adoptingcommunication synchronization using a SYNC signal as shown in FIGS. 2and 3, there is provided a liquid crystal display apparatus of thepresent invention which uses the liquid crystal device according to thepresent invention as a display panel portion.

Referring to FIG. 2, a liquid crystal display apparatus 101 includes agraphic controller 102, a display panel 103, a scanning line drivecircuit 104, a data line drive circuit 105, a decoder 106, a scanningsignal generator 107, a shift resistor 108, a line memory 109, a datasignal generator 110, a drive control circuit 111, a graphic centralprocessing unit (GCPU) 112, a host central processing unit (host CPU)113, and an image data storage memory (VRAM) 114.

Image data are generated in the graphic controller 102 in an apparatusbody and transferred to a display panel 103 by signal transfer means.The graphic controller 102 principally comprises a CPU (centralprocessing unit, hereinafter referred to as "GCPU") 112 and a VRAM(video-RAM, image data storage memory) 114 and is in charge ofmanagement and communication of image data between a host CPU 113 andthe liquid crystal display apparatus (FLCD) 101. The control of thedisplay apparatus is principally performed by the graphic controller102. A light source (not shown) is disposed at the back of the displaypanel 103.

Hereinbelow, the present invention will be explained more specificallywith reference to examples. It is however to be understood that thepresent invention is not restricted to these examples.

EXAMPLE 1

Three chiral smectic liquid crystal compositions (1), (2) and (3) wereprepared by mixing the following compounds (having the indicatedstructural formulae and phase transition temperatures (° C.))) in theproportions indicated below.

A/B₁ /B₂ /B₃ /C₁ =50/15/10/15/10 (wt. %) (C₁ : C₁ -1 for Composition(1), C₁ -2 for Composition (2) and C₁ --3 for Composition (3)) ##STR32##

In the above phase transition series, Sx denotes a smectic phase(unidentified); Sc denotes a smectic C phase; S_(A) denotes a smectic Aphase; and Iso denotes an isotropic phase.

Each of liquid crystal cells was prepared as follows.

To one glass plate provided with an ITO film, a solution of a polyimideprecursor (providing a polyimide having a recurring unit of the formulashown below) in a mixture solvent (n-methylpirrolidone(NMP)/n-butylcellosolve (nBC)=2/1) was applied by spin coating. The thuscoated glass plate was subjected to hot curing treatment and a rubbingtreatment. ##STR33##

To another glass plate provided with an ITO film, a solution of a silanecoupling agent comprising octadecyltriethoxysilane was applied by spincoating, followed by hot curing.

After silica beads as a spacer were dispersed on one of theabove-treated two glass plates, the two glass plates were applied toeach other to form a blank cell having a cell gap of 1.8 μm.

Into the thus-prepared liquid crystal cells, the above-prepared liquidcrystal compositions (1) to (3) heated into an isotropic liquid wereinjected, respectively, by a capillary method. Each of the liquidcrystal cells was then gradually cooled to room temperature to prepare aliquid crystal device according to the present invention.

Each of the thus-prepared liquid crystal devices using the liquidcrystal compositions (1) to (3), respectively, was subjected tomeasurement of an apparent tilt angle θa, a contrast ratio and athreshold value (for switching). The results are shown in Table 5appearing hereinafter.

                  TABLE 5                                                         ______________________________________                                                                 (at 40° C.)                                                                        Threshold                                Composition                                                                            Chiral    θa          value                                    No.      dopant    (degrees)                                                                              Contrast (μsec)                                ______________________________________                                        (1)      C.sub.1 -1                                                                              21.4     35       62                                       (2)      C.sub.1 -2                                                                              18.9     32       60                                       (3)      C.sub.1 -3                                                                              19.9     31       49                                       ______________________________________                                    

Herein, the respective characteristics were evaluated or measured asfollows.

Apparent tilt angle θa

(A half of an angle between optical axes in two stable states (memorystate))

An liquid crystal device sandwiched between right angle cross nicolpolarizes was supplied with a single pulse of one polarity exceeding thethreshold voltage of the liquid crystal and was then rotated under noelectric field horizontally relative to the polarizers to find a firstextinction position. Then, the liquid crystal device was supplied with asingle pulse of the opposite polarity exceeding the threshold voltage ofthe ferroelectric liquid crystal and was then rotated under no electricfield relative to the polarizers to find a second extinct position. Anapparent tilt angle θa was measured as a half of the angle between thefirst and second extinct positions.

Contrast ratio

The contrast ratio was measured by fixing a stage providing the darkestoptical axis by means of a photomultiplier (available from HamamatsuPhotonics K.K.) under observation through a polarizing microscope andunder application of a rectangular pulse having a switching signalwaveform (voltage: ±5 V, pulse width: 1.2 times that of a thresholdpulse width) shown in FIG. 4, thereby to find an output value for a dark(black) state and an output value for a bright (white) state. Thecontrast ratio was determined by dividing the output value for the whitestate by the output value for the black state.

Threshold value

The threshold value was determined by using a switching signal shown inFIG. 4 and gradually changing a pulse width to find a minimum pulsewidth (μsec) for effecting switching.

Layer inclination angle δ

The layer inclination angle δ was measured according to a methoddescribed in Jpn. J. Appl. Phys. 27, p. L725 (1988).

EXAMPLE 2

A liquid crystal composition (4) was prepared in the same manner as inExample 1 except that the respective components were mixed in thefollowing proportions. Composition (4):

A/B₁ /B₂ /B₃ /C₁ -1=1 80/3/3/4/10 (wt. %)

The liquid crystal composition was evaluated in the same manner as inExample 1 except for further measuring a layer inclination angle δ.

The results are shown below.

θa: 22.3 degrees,

Threshold value: 48 μsec,

Contrast: 52, and

δ=2 degrees.

REFERENCE EXAMPLE 1

A liquid crystal composition (5) was prepared and evaluated in the samemanner as in the case of the liquid crystal composition (1) used inExample 1 except that the chiral dopant C₁ -1 was changed to thefollowing chiral dopant. ##STR34##

The results are shown below.

θa: 17 degrees.

Threshold value: A clear threshold value was not obtained although apulse width was increased to 5 msec.

Contrast: 8.3 at a pulse width of 100 sec.

REFERENCE EXAMPLE 2

A liquid crystal composition (6) was prepared in the same manner as inthe case of the liquid crystal composition (1) used in Example 1 exceptthat the chiral dopant C₁ -1 was changed to the following chiral dopant.##STR35##

However, the liquid crystal composition (6) caused precipitation of aninsoluble component at room temperature, thus showing a poor mutualsolubility.

EXAMPLE 3

Liquid crystal cells were prepared in the same manner as in Examples 1and 2 except that the polyimide alignment film was changed to apolyimide film having a recurring unit (P1) below or a recurring unit(P2) below and the liquid crystal compositions (1)-(4) used in Examples1 and 2 were used. ##STR36##

All of the resultant liquid crystal cells (devices) using the polyimidefilm having the recurring unit (P1) or (P2) showed a very good alignmentstate over the entire cell similarly as in the case of polyimide filmsused in Examples 1 and 2.

EXAMPLE 4

Two liquid crystal compositions (7) and (8) were prepared by mixing thefollowing compounds (A, B₁, B₂ and B₃ are identical to those used inExample 1) in the indicated proportions, respectively. (composition)(components) (mixing ratio by wt. %)

(7) A/B₁ /B₂ /B₃ /C₂ 80/3/3/4/10

(8) A/B₁ /B₂ /B₃ /C₂ 50/15/10/15/10 ##STR37##

Two liquid crystal devices were prepared and evaluated in respects ofthe layer inclination angle δ and the contrast ratio in the same manneras in Example 1 by using the liquid crystal compositions (7) and (8),respectively.

The results are shown below.

    ______________________________________                                        Composition     Contrast δ (deg.)                                       ______________________________________                                        (7)             54       3                                                    (8)             39       --                                                   ______________________________________                                    

EXAMPLE 5

Two liquid crystal compositions (9) and (10) were prepared in the samemanner as in the case of the liquid crystal composition (7) used inExample 4 except that the chiral dopant C₂ was changed to opticallyactive compounds (as a chiral dopant) (Ex. Comp. Nos. 4-7 and 4-37),respectively.

The liquid crystal compositions (9) and (10) were subjected tomeasurement of a contrast ratio in the same manner as in Example 4.

As a result, the liquid crystal composition (9) provided a contrastratio of 47 and the liquid crystal composition (10) provided a contrastratio of 41.

EXAMPLE 6

Liquid crystal cells were prepared in the same manner as in Examples 4and 5 except that the polyimide alignment film was changed to apolyimide film having a recurring unit (P1) below or a recurring unit(P2) below and the liquid crystal compositions (7)-(10) used in Examples4 and 5 were used. ##STR38##

All of the resultant liquid crystal cells (devices) using the polyimidefilm having the recurring unit (P1) or (P2) showed a very good alignmentstate over the entire cell similarly as in the case of polyimide filmsused in Example 4 and 5 .

REFERENCE EXAMPLE 3

A liquid crystal composition (11) was prepared and evaluated in respectof the contrast ratio in the same manner as in the case of the liquidcrystal composition (7) used in Example 4 except that the chiral dopantC₂ was changed to the following chiral dopant. ##STR39##

The liquid crystal composition (11) provided a poor contrast ratio of6.2.

REFERENCE EXAMPLE 4

A liquid crystal composition (12) was prepared in the same manner as inthe case of the liquid crystal composition (7) used in Example 4 exceptthat the chiral dopant C₂ was changed to the following chiral dopant.##STR40##

However, the liquid crystal composition (12) caused precipitation of aninsoluble component at room temperature, thus showing a poor mutualsolubility.

EXAMPLE 7

Two liquid crystal compositions (13) and (14) were prepared by mixingthe following compounds (A, B₁, B₂ and B₃ are identical to those used inExample 1) in the indicated proportions, respectively.

(composition) (components) (mixing ratio by wt. %)

(13) A/B₁ /B₂ /B₃ /C₃ 80/3/3/4/10

(14) A/B₁ /B₂ /B₃ /C₃ 50/15/10/15/10 ##STR41##

Two liquid crystal devices were prepared and evaluated in respects ofthe layer inclination angle δ and the contrast ratio in the same manneras in Example 1 by using the liquid crystal compositions (13) and (14),respectively.

The results are shown below.

    ______________________________________                                        Composition     Contrast δ (deg.)                                       ______________________________________                                        (13)            65       3                                                    (14)            45       --                                                   ______________________________________                                    

EXAMPLE 8

Two liquid crystal compositions (15) and (16) were prepared in the samemanner as in the case of the liquid crystal composition (13) used inExample 7 except that the chiral dopant C₃ was changed to opticallyactive compounds (as a chiral dopant) (Ex. Comp. Nos. 5-9 and 5-12),respectively.

The liquid crystal compositions (15) and (16) were subjected tomeasurement of a contrast ratio in the same manner as in Example 7.

As a result, the liquid crystal composition (15) provided a contrastratio of 39 and the liquid crystal composition (16) provided a contrastratio of 43.

EXAMPLE 9

Liquid crystal cells were prepared in the same manner as in Examples 7and 8 except that the polyimide alignment film was changed to apolyimide film having a recurring unit (P1) below or a recurring unit(P2) below and the liquid crystal compositions (13)-(16) used inExamples 7 and 8 were used. ##STR42##

All of the resultant liquid crystal cells (devices) using the polyimidefilm having the recurring unit (P1) or (P2) showed a very good alignmentstate over the entire cell similarly as in the case of polyimide filmsused in Examples 7 and 8.

REFERENCE EXAMPLE 5

A liquid crystal composition (17) was prepared and evaluated in respectof the contrast ratio in the same manner as in the case of the liquidcrystal composition (14) used in Example 7 except that the chiral dopantC₃ was changed to the following chiral dopant. ##STR43##

The liquid crystal composition (17) provided a poor contrast ratio of6.2.

EXAMPLE 10

Two liquid crystal compositions (18), (19) and (20) were prepared bymixing the following compounds (A, B₁, B₂ and B₃ are identical to thoseused in Example 1) in the indicated proportions, respectively.

A/B₁ /B₂ /B₃ /C₄ 50/15/10/15/10 (wt. %) ##STR44##

Two liquid crystal devices were prepared and evaluated in the samemanner as in Example 1 by using the liquid crystal compositions (18),(19) and (20), respectively.

The results are shown in Table 6 below.

                  TABLE 6                                                         ______________________________________                                                                 (at 40° C.)                                                                        Threshold                                Composition                                                                            Chiral    θa          value                                    No.      dopant    (degrees)                                                                              Contrast (μsec)                                ______________________________________                                        (18)     6-15      24.4     43       14                                       (19)     6-19      19.0     47       97                                       (20)     6-36      17.2     41        8                                       ______________________________________                                    

EXAMPLE 11

A liquid crystal composition (21) was prepared in the same manner as inthe case of the liquid crystal composition (18) used in Example 10except that the respective components were mixed in the followingproportions.

Composition (21):

A/B₁ /B₂ /B₃ /C₄ (Ex. Comp. No. 6-15)=80/3/3/4/10 (wt. %)

The liquid crystal composition was evaluated in the same manner as inExample 1 except for further measuring a layer inclination angle δ.

The results are shown below.

θa: 21.6 degrees,

Threshold value: 10 μsec,

Contrast: 58, and

δ=3 degrees.

EXAMPLE 12

Liquid crystal cells were prepared in the same manner as in Examples 10and 11 except that the polyimide alignment film was changed to apolyimide film having a recurring unit (P1) below or a recurring unit(P2) below and the liquid crystal compositions (18)-(21) used inExamples 10 and 11 were used. ##STR45##

All of the resultant liquid crystal cells (devices) using the polyimidefilm having the recurring unit (P1) or (P2) showed a very good alignmentstate over the entire cell similarly as in the case of polyimide filmsused in Examples 10 and 11.

REFERENCE EXAMPLE 6

Liquid crystal compositions were prepared by mixing the followingcompounds in the indicated proportions.

A/B₁ /B₂ /B₃ /Chiral=25/23/20/22/10 (wt. %)

In the above, A, B₁, B₂ and B₃ are identical to those used in Example 1and "Chiral" is each of the respective chirl dopants used in Examples1-12.

When the thus-prepared liquid crystal compositions were subjected tomeasurement of a contrast ratio in the same manner as in Example 1, allof the liquid crystal compositions provided a contrast ratio below 10.

As described above, according to the invention, there is provided aliquid crystal composition, particularly a chiral smectic liquid crystalcomposition, showing a high mutual solubility of components thereof,providing a liquid crystal molecular layer having a bookshelf structureor a structure closer thereto having a small layer inclination angle,and exhibiting a good alignment state of the liquid crystal layer. As aresult, a (chiral smectic or ferroelectric) liquid crystal device usingthe liquid crystal composition according to the present inventionprovides various improved properties such as a high responsiveness, ahigh contrast ratio, a high definition, a high brightness and a largepicture area.

In addition, when the liquid crystal device is used as a display devicein combination with a light source, drive circuit, etc., a liquidcrystal apparatus, such as a liquid crystal display apparatus, providinggood display characteristics can be realized.

What is claimed is:
 1. A liquid crystal composition comprising:at leastone fluorine-containing mesomorphic compound (a) having smectic phase orhaving latent smectic phase and represented by the following formula(I): ##STR46## in which B₁, D₁ and F₁ independently denote ##STR47## a,b and c independently denote an integer of 0-3 with the proviso thata+b+c is at least 2;M₁ and N₁ independently denote --COO--, --OCO--,--COS--, --SCO--, --COSe--, --SeCO--, --COTe--, --TeCO--, --(CH₂CH₂)_(d) -- wherein d is an integer of 1-4, --CH═CH--, --CH═N--,--N═CH--, --CH₂ O--, --OCH₂ --, --CO--, --O-- or a single bond; X, Y andZ independently denote --H, --Cl, --F, --Br, --I, --OH, --OCH₃, --CN, or--NO₂ ; and l, m and n independently denote an integer of 0-4; G₁ is--COO--C_(e) H_(2e) --, --O--C_(e) H_(2e) --, --C_(e) H_(2e) --,--OSOO--, --OOSO--, --SOO--, --SOOC_(e) H_(2e) --, --OC_(e) H_(2e)--OC_(e') H_(2e') --, --C_(e) H_(2e) --N(C_(p) H_(2p+1))--SO₂ -- or--C_(e) H_(2e) --N(C_(p) H_(2p+1))--CO-- wherein e and e' independentlydenote an integer of 1-20 and p is an integer of 0-4; A₁ is a linear orbranched group represented by --O--C_(f) H_(2f) --O--C_(g) H_(2g+1),--C_(f) H_(2f) --O--C_(g) H_(2g+1), --C_(f) H_(2f) --R', --O--C_(f)H_(2f) --R', --COO--C_(f) H_(2f) --R' or --OCO--C_(f) H_(2f) --R'wherein R' is --Cl, --F, --CF₃, --NO₂, --CN, --H, --COO--C_(f')H_(2f'+1) or --OCO--C_(f') H_(2f'+1) in which f, f' and g independentlydenote an integer of 1-20; and R is .paren open-st.C_(x') F_(2x')O)_(z') C_(y) F_(2y+1) wherein x' is independently an integer of 1-10for each C_(x') F_(2x') O group, y is an integer of 1-10, and z' is aninteger of 1-6; and at least one optically active compound (b)represented by the following formula (II):

    R.sub.0 --A.sub.0 --R.sub.1                                (II),

wherein A₀ is a mesogen group consisting one to four divalent groupseach connected by a single bond, --COO--, --OCO--, --CH₂ O--, or --OCH₂-- and each capable of having one or two substituents selected from thegroup consisting of F, Cl, Br, CH₃, CF₃ and CN, the divalent group beingselected from the group consisting of 1,4-phenylene; pyridine-2-,5-diyl;pyrimidine-2,5-diyl; pyrazine-2,5-diyl; pyridazine-3,6-diyl;1,4-cyclohexylene; 1,3-dioxane-2,5-diyl; 1,3-dithiane-2,5-diyl;thiophene-2,5-diyl; thiazole-2,5-diyl; thiadiazole-2,5-diyl;benzoxazole-2,5-diyl; benzoxazole-2,6-diyl; benzothiazole-2,5-diyl;benzothiazole-2,6-diyl; benzofuran-2,5-diyl; benzofuran-2,6-diyl;quinoxaline-2,6-diyl; quinoline-2,6-diyl; 2,6-naphthylene;indan-2,5-diyl; 2-alkylindan-2,5-diyl having a linear or branched alkylgroup having 1-18 carbon atom; indanone-2,6-diyl;2-alkylindanone-2,6-diyl having a linear or branched alkyl group having1-18 carbon atoms; coumaran-2,5-diyl; and 2-alkylcoumaran-2,5-diylhaving a linear or branched alkyl group having 1-18 carbon atoms; and R₀and R₁ independently denote a linear or branched alkyl group having 1-18carbon atoms; each of the alkyl groups R₀ and R₁ being capable ofincluding at least one --CH₂ -- group which can be replaced by --Y--,--Y--CO--, --CO--Y--, --CO--, --OCOO--, --CH═CH-- or --.tbd.CC-- inwhich Y is O or S; and at least one of R₀ and R₁ having at least oneasymmetric carbon atom directly connected with F, CF₃ or CH₃, R₀ and R₁satisfying any one of the following conditions (i) to (iv):(i) any oneof R₀ and R₁ is represented by the following formula: ##STR48## in whichR³⁵ is a linear or branched alkyl group having 1-18 carbon atoms; R³³ is--CH₂ -- or --CO--; R³⁴ is H or CH₃ ; X³³ is a single bond or --CH₂ --when R³³ is --CO--, or X³³ is a single bond, --CO-- or --CH₂ -- when R³³is --CH₂ --; and C* is an asymmetric carbon atom; (ii) any one of R₀ andR₁ is represented by the following formula: ##STR49## in which R⁴³ is alinear or branched alkyl group having 1-10 carbon atoms; R⁴³ is --O--,--COO--, --OCH₂ --, --OCH₂ CH₂ --, --OCOCH₂, --CH₂ O--, --COOCH₂ CH₂ --,--CH₂ OCH₂ CH₂ -- or --CH₂ COOCH₂ --; and C* is an asymmetric carbonatom; (iii) any one of R₀ and R₁ is represented by the followingformula: ##STR50## in which R⁵³ is a linear or branched alkyl grouphaving 1-18 carbon atoms; L52 is 0 or 1; X⁵³ is a single bond, --CO-- or--C₂ -- when L52 is 0, or X⁵³ is a single bond or --CH₂ -- when L52 is1; X⁵⁴ is --COO-- or --O--; L53 is 0 or 1; and C* is an asymmetriccarbon atom; and (iv) both of R₀ and R₁ are an alkyl group having anasymmetric carbon atom directly connected with F, CF₃ or CH₃.
 2. Acomposition according to claim 1, wherein the compound (a) of theformula (I) is a fluorine-containing mesomorphic compound represented bythe following formula (I'): ##STR51## in which n2 is an integer of 5-10;andR" is (--C_(x") F_(2x") O)_(z") C_(y') F_(2') +1 wherein, x" isindependently an integer of 1-3 for each C_(x") F_(2x") O group y' is aninteger of 1-4, and z" is an integer of 1--3.
 3. A composition accordingto claim 1, which comprises at least 30 wt. % of a fluorine-containingmesomorphic compound (a).
 4. A composition according to claim 1, whichcomprises at least 50 wt. % of a fluorine-containing mesomorphiccompound (a).
 5. A composition according to claim 1, wherein thecompound (b) of the formula (II) is an optically active compoundrepresented by the following formula (III): ##STR52## in which R³² is alinear or branched alkyl group having 1-18 carbon atoms capable ofincluding at least one --CH₂ -- group which can be replaced by --Y³ --,--Y³ --CO--, --CO--Y³ --, --CO--, --OCOO--, --CH═CH-- or --C.tbd.C--wherein Y³ is O or S;R³⁵ is a linear or branched alkyl group having 1-18carbon atoms; m32 is 0, 1 or 2; R³³ is --CH₂ -- or --CO--; R³⁴ is H orCH₃ ; A³², A³³ and A³⁴ independently denote a single bond,1,4-phenylene; pyridine-2,5-diyl; pyrimidine-2,5-diyl;pyrazine-2,5-diyl; pyridazine-3,6-diyl; 1,4-cyclohexylene;1,3-dioxane-2,5-diyl; 1,3-dithiane-2,5-diyl; thiophene-2,5-diyl;thiazole-2,5-diyl; thiadiazole-2,5-diyl; benzoxazole-2,5-diyl;benzoxazole-2,6-diyl; benzothiazole-2,5-diyl; benzothiazole-2,6-diyl;benzofuran-2,5-diyl; benzofuran-2,6-diyl; quinoxaline-2,6-diyl;quinoline-2,6-diyl; 2,6-naphthylene; indan-2,5-diyl;2-alkylindan-2,5-diyl having a linear or branched alkyl group having1-18 carbon atom; indanone-2,6-diyl; 2-alkylindanone-2,6-diyl having alinear or branched alkyl group having 1-18 carbon atoms;coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl having a linear orbranched alkyl group having 1-18 carbon atoms; X³² is a single bond,--COO--, --OCO--, --CH₂ O-- or --OCH₂ --; X³³ is a single bond or --CH₂-- when R³³ is --CO--, Or X³³ is a single bond, --CO-- or --CH₂ -- whenR³³ is --CH₂ --; C* is an asymmetric carbon atom; and A³², A³³ and A³⁴each can have one or two substituents selected from the group consistingof F, Cl, Br, CH₃, CF₃ and CN and cannot be single bond at the sametime.
 6. A composition according to claim 5, wherein R³² and R³⁵independently denote a linear or branched alkyl group; m32 is 0; R³³ is--CH₂ -- or --CO--; R³⁴ is H or CH₃ ; A³³ is ##STR53## A³⁴ is ##STR54##and X³³ is a single bond or --CH₂ -- when R³³ is --CO--, or X³³ is asingle bond, --CO-- or --CH₂ -- when R³³ is --CH₂ --.
 7. A compositionaccording to claim 5, which comprises below 50 wt. % of an opticallyactive compound of the formula (III).
 8. A composition according toclaim 1, wherein the compound (b) of the formula (II) is an opticallyactive compound represented by the following formula (IV): ##STR55## inwhich R⁴² is a linear or branched alkyl group having 1-18 carbon atomscapable of including at least one --CH₂ -- group which can be replacedby --Y⁴ --, --Y⁴ --CO--, --CO--Y⁴ --, --CO--, --OCOO--, --CH═CH-- or--C.tbd.C-- wherein Y⁴ is O or S;R⁴³ is a linear or branched alkyl grouphaving 1-10 carbon atoms; m42 is 0, 1 or 2; A⁴², A⁴³ and A⁴⁴independently denote a single bond, 1,4-phenylene; pyridine-2,5-diyl;pyrimidine-2,5-diyl; pyrazine-2,5-diyl; pyridazine-3,6-diyl;1,4-cyclohexylene; 1,3-dioxane-2,5-diyl; 1,3-dithiane-2,5-diyl;thiophene-2,5-diyl; thiazole-2,5-diyl; thiadiazole-2,5-diyl;benzoxazole-2,5-diyl; benzoxazole-2,6-diyl; benzothiazole-2,5-diyl;benzothiazole-2,6-diyl; benzofuran-2,5-diyl; benzofuran-2,6-diyl;quinoxaline-2,6-diyl; quinoline-2,6-diyl; 2,6-naphthylene;indan-2,5-diyl; 2-alkylindan-2,5-diyl having a linear or branched alkylgroup having 1-18 carbon atom; indanone-2,6-diyl;2-alkylindanone-2,6-diyl having a linear or branched alkyl group having1-18 carbon atoms; coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl havinga linear or branched alkyl group having 1-18 carbon atoms; X⁴² is asingle bond, --COO--, --OCO--, --CH₂ O-- or --OCH₂ --; X⁴³ is --O--,--COO--, --OCH₂ --, --OCH₂ CH₂ --, --OCOCH₂ --, --CH₂ O--, --COOCH₂ CH₂--, --CH₂ OCH₂ CH₂ -- or --CH₂ COOCH₂ ; C* is an asymmetric carbon atom;and A⁴², A⁴³ and A⁴⁴ each can have one or two substituents selected fromthe group consisting of F, Cl, Br, CH₃, CF₃ and CN and cannot be asingle bond at the same time.
 9. A composition according to claim 8,wherein R⁴² is a linear or branched alkyl or alkoxy group having 1-18carbon atoms; R⁴³ is a linear or branched alkyl group having 1-10 carbonatoms; M42 is 0; R⁴² is ##STR56## A⁴³ is ##STR57## and X⁴³ is --O--,--OCH₂ --, --COO--, --COOCH₂ CH₂ -- or --OCH₂ CH₂ --.
 10. A compositionaccording to claim 8, which comprises below 50 wt. % of an opticallyactive compound of the formula (IV).
 11. A composition according toclaim 1, wherein the compound (b) of the formula (II) is an opticallyactive compound represented by the following formula (V): ##STR58## inwhich R₅₂ is a linear or branched alkyl group having 1-18 carbon atomscapable of including at least one --CH₂ -- group which can be replacedby --Y⁵ --, --Y⁵ --CO--, --CO--Y⁵ --, --CO--, --OCOO--, --CH═CH-- or--C.tbd.C-- wherein Y⁵ is O or S;R⁵³ is a linear or branched alkyl oralkoxy group having 1-10 carbon atoms; M52 is 0, 1 or 2; A⁵², A⁵³ A⁵⁴independently denote a single bond, 1,4-phenylene; pyridine-2,5-diyl;pyrimidine-2,5-diyl; pyrazine-2,5-diyl; pyridazine-3,6-diyl;1,4-cyclohexylene; 1,3-dioxane-2,5-diyl; 1,3-dithiane-2,5-diyl;thiophene-2,5-diyl; thiazole-2,5-diyl; thiadiazole-2,5-diyl;benzoxazole-2,5-diyl; benzoxazole-2,6-diyl; benzothiazole-2,5-diyl;benzothiazole-2,6-diyl; benzofuran-2,5-diyl; benzofuran-2,6-diyl;quinoxaline-2,6-diyl; quinoline-2,6-diyl; 2,6-naphthylene;indan-2,5-diyl; 2-alkylindan-2,5-diyl having a linear or branched alkylgroup having 1-18 carbon atom; indanone-2,6-diyl;2-alkylindanone-2,6-diyl having a linear or branched alkyl group having1-18 carbon atoms; coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl havinga linear or branched alkyl group having 1-18 carbon atoms; X⁵² is asingle bond, --COO--, --OCO--, --CH₂ O-- or --OCH₂ --; X⁵³ is a singlebond, --CO-- or --CH₂ -- when L52 is 0 or X⁵³ is a single bond or --CH₂-- when L52 is 1; L52 and L53 are 0 or 1; C* is an asymmetric carbonatom; and A⁵², A⁵³ and A⁵⁴ each can have one or two substituentsselected from the group consisting of F, Cl, Br, CH₃, CF₃ and CN andcannot be a single bond at the same time.
 12. A composition according toclaim 11, wherein R⁵² is a linear or branched alkyl or alkoxy grouphaving 1-18 carbon atoms; R⁵³ is a linear or branched alkyl group having1-10 carbon atoms; m52 and L52 are 0; A⁵² is ##STR59## A⁵³ is ##STR60##and X⁵³ is a single bond or --CO--.
 13. A composition according to claim4, which comprises below 50 wt. % of an optically active compound of theformula (V).
 14. A composition according to claim 1, wherein thecompound (b) of the formula (II) is an optically active compoundrepresented by the following formula (VI):

    R.sup.62 --(A.sup.62 --X.sup.62).sub.m62 --A.sup.63 --A.sup.64 --X.sup.63 --R.sup.63                                                (VI),

in which R⁶² and R⁶³ independently denote a linear or branched alkylgroup having 1-18 carbon atoms and at least one asymmetric carbon atomdirectly connected with F, CF₃ or CH₃ and capable of including at leastone --CH₂ -- group which can be replaced by --Y⁶ --, --Y⁶ --CO--,--CO--Y⁶ --, --CO--, --OCOO--, --CH═CH-- or --C.tbd.C-- wherein Y⁶ is Oor S; m62 is 0, 1 or 2; A⁶², A⁶³ and A⁶⁴ independently denote a singlebond, 1,4-phenylene; pyridine-2,5-diyl; pyrimidine-2,5-diyl;pyrazine-2,5-diyl; pyridazine-3,6-diyl; 1,4-cyclohexylene;1,3-dioxane-2,5-diyl; 1,3-dithiane-2,5-diyl; thiophene-2,5-diyl;thiazole-2,5-diyl; thiadiazole-2,5-diyl; benzoxazole-2,5-diyl;benzoxazole-2,6-diyl; benzothiazole-2,5-diyl; benzothiazole-2,6-diyl;benzofuran-2,5-diyl; benzofuran-2,6-diyl; quinoxaline-2,6-diyl;quinoline-2,6-diyl; 2,6-naphthylene; indan-2,5-diyl;2-alkylindan-2,5-diyl having a linear or branched alkyl group having1-18 carbon atom; indanone-2,6-diyl; 2-alkylindanone-2,6-diyl having alinear or branched alkyl group having 1-18 carbon atoms;coumaran-2,5-diyl; or 2-alkylcoumaran-2,5-diyl having a linear orbranched alkyl group having 1-18 carbon atoms; and X⁶² and X⁶³independently denote a single bond, --COO--, --OCO--, --CH₂ O-- or--OCH₂ ; and A⁶², A⁶³ and A⁶⁴ each can have one or two substituentsselected from the group consisting of F, Cl, Br, CH₃, CF₃ and CN andcannot be a single bond at the same time.
 15. A composition according toclaim 14, wherein R⁶³ in the formula (VI) is represented by thefollowing formula: ##STR61## in which R⁶⁴ is a linear or branched alkylgroup having 1-16 carbon atoms.
 16. A composition according to claim 14,wherein R⁶² in the formula (VI) is represented by the following formula:##STR62## in which R⁶⁵ is a linear or branched alkyl group having 1-16carbon atoms, and d is an integer of 1-6.
 17. A composition according toclaim 14, wherein m62 is 0; A⁶³ is ##STR63## and A⁶⁴ is ##STR64##
 18. Acomposition according to claim 14, which comprises below 50 wt. % of anoptically active compound of the formula (VI).
 19. A liquid crystaldevice, comprising a liquid crystal composition according to any one ofclaims 1, 2, 3, 4, 5, 18 and
 25. 20. A device according to claim 19,comprising a pair of opposite electrode plates and the liquid crystalcomposition disposed between the electrode plates.
 21. A deviceaccording to claim 20, which further comprises an alignment controllayer formed on at least one of the electrode plates.
 22. A deviceaccording to claim 21, wherein the alignment control layer comprises apolyimide having a recurring unit represented by the following formula(VII): ##STR65## in which R₇₁ is ##STR66## R₇₂ and R₇₄ independentlydenote ##STR67## R₇₃ is a single bond or --O--; and 1 is 0, 1 or
 2. 23.A display method, comprising:providing a liquid crystal compositionaccording to claim 1; and controlling the alignment direction of liquidcrystal molecules in accordance with image data to effect display.
 24. Aliquid crystal apparatus comprising a liquid crystal device according toclaim
 19. 25. A composition according to claim 1, further comprising atleast one fluorine-containing mesomorphic compound having smectic phaseor having latent smectic phase and represented by the following formula(I"): ##STR68## in which B₁, D₁ and F₁ independently denote ##STR69## a,b and c independently denote an integer of 0-3 with the proviso thata+b+c is at least 2;M₁ and N₁ independently denote --COO--, --OCO--,--COS--, --SCO--, --COSe--, --SeCO--, --COTe--, --TeCO--, --(CH₂CH₂)_(d) -- wherein d is an integer of 1-4, --CH═CH--, --CH═N--,--N═CH--, --CH₂ O--, --OCH₂ --, --CO--, --O-- or a single bond; X, Y andZ independently denote --H, --Cl, --F, --Br, --I, --OH, --OCH₃, --CN, or--NO₂ ; and l, m and n independently denote an integer of 0-4; G₁ is--COO--C_(e) H_(2e) --, --O--C_(e) H_(2e) --, --C_(e) H_(2e) --,--OSOO--, --OOSO--, --SOO--, --SOOC_(e) H_(2e) --, --OC_(e) H_(2e)--OC_(e') H_(2e') --, --C_(e) H_(2e) --N(C_(p) H_(2p+1))--SO₂ -- or--C_(e) H_(2e) --N(C_(p) H_(2p+1))--CO-- wherein e and e' independentlydenote an integer of 1-20 and p is an integer of 0-4; A₁ is a linear orbranched group represented by --O--C_(f) H_(2f) --O--C_(g) H_(2g+1),--C_(f) H_(2f) --O--C_(g) H_(2g+1), --C_(f) H_(2f) --R', --O--C_(f)H_(2f) --R', --COO--C_(f) H_(2f) --R' or --OCO--C_(f) H_(2f) --R'wherein R' is --Cl, --F, --CF₃, --NO₂, --CN, --H, --COO--C_(f')H_(2f'+1) or --OCO--C_(f') H_(2f'+1) in which f, f' and g independentlydenote an integer of 1-20; and R' is --C_(x) F_(2x+1) wherein x is aninteger of 1-20.